Making the Game Harder

This page is intended for players who finish the game frequently on the highest difficulty and would like to keep the challenge alive.

Naturally it is quite easy to handicap yourself while playing the game: using only conventional weaponry, no armor, fighting only on night missions, etc. Some of these situations are detailed here, in addition to exploits/cheats/tactics that make the game easier, which you might want to refrain from using.

Feel free to try any of these ideas (or all of them!). Some may make the game very hard or even impossible to win.

No Psionics

Psionics and Psi-Amps can completely imbalance the game in favor of the human player. Even one Psi-Amp is bad news for aliens, and with training and screening, a squad full of psionic troops can eventually mind-control all the aliens during the first turn (even Cyberdiscs and Sectopods). This turns combat into a cakewalk, which is not nearly as much fun as sweating your way around every single corner. Therefore, one of the most important things you can do to make the game more challenging is to avoid using Psi-Amps.

Significantly less unbalancing is the use of Psi Labs to screen troops (and perhaps also increase their Psionic Defense). However, for an even greater challenge, you can avoid using Psi Labs altogether, which forces you to rely on combat trauma to find out which of your troops are psi weaklings.

No Mind Probes

Much less powerful than Psionics is the advantage from using Mind Probes since those devices can be used to screen aliens for their rank (for capture or to identify the threat they pose), or to check if they are able to reaction fire. Mind control can also provide most of this information, so restricting use of Mind Probes is most significant when combined with a ban on Psi-Amps.

Don't Use Game Exploits

Plenty of Exploits have been identified for UFO: Enemy Unknown. Their influence on Battlescape/Geoscape varies, here's a list of those that you should particularly avoid and their consequences.

Alien Inventory Screen

Although you are not supposed to be able to access an alien's inventory screen when you mind control it, there is a way to do so. This allows for nasty things like priming grenades and dropping them at the feet of the alien. Another thing to consider is to stop using Psionics all together (see above).

Faulty Collision Detection

A full description can be found here. These exploits allow you to attack through walls or other solid objects, and bypass map chokepoints (such as UFO doors) which can be used by the aliens to ambush your soldiers.

Free Wages/Manufacturing/Fuel

These exploits are commonly used to prevent your finances from going negative at the end of the month or to keep your planes flying for free. The Free Wages avoids having to pay your scientists/engineers/soldiers' salaries. Most of your monthly expenses are made of those, so having to pay for your 250 scientists makes financial matters more hard to deal with. If you have never played the game without using these exploits, you've never really played the strategic game - it is MUCH harder to succeed when you have to pay your way.

UFO Redux

Increases your loot, income, score and experience up to two or even three times normal, and in turn boosts your technology progress. If you haven't been using this exploit, don't start now!

Scared Of The Dark?

If you regularly avoid all night missions using these exploits, shame on you! Grab the flares and IC rounds, and be afraid, be very afraid!

Don't Use Beneficial XComUtil Options

Many XComUtil options (or similar options from other 'game enhancers' or variant games) make the game easier to win. As XComUtil was designed to make the game harder, it's a shame that the options that make the game easier are not flagged up more conspicuously.

Improved Starting Base

This actually hands you $4.5 million on a plate. In fact, it's far better than $4.5 million in cash, because the stuff you would buy with the $4.5 million is already built and/or in situ in your base. This option gives you a 1-2 month head start on the aliens, who don't get any advantages. So while the intent is to alleviate boring and repetitive play for experienced players, the net effect is to reduce the challenge.

Alternate Starting Base

This option is much less of a boon, but it still in effect hands you the $800K it would cost to reorganise your normal (badly layed out) starting base. And you get to do useful things with your base instead, during the month it would've take to reorganise it. Still, this is only a minor buff, and not a big deal compared to the Improved Starting Base. And the initial base layout is infuriating.

Improved Tanks

Players often forget that they routinely take this option to give human-technology tank chassis the same armour level as the hybrid, alien-alloy-armoured tank chassis. This has a big difference on the viability of the starting tanks (Cannon Tank, Rocket Tank, Laser Tank). Scott Jones believed that these HWPs were not viable without this mod. Perhaps he was right. Nonetheless, if you use this option, you are making the early game significantly easier. Assuming you believe an HWP is better than 4 soldiers - and if you don't believe that, you shouldn't care about using this option anyway.

Improved Weapons

This option improves the Pistol, Heavy Laser, and High Explosive. The Heavy Laser mod is fairly subtle and is intended to make "an otherwise useless item, useful". It does not create an uber-weapon. The Pistol improvement is arguably unnecessary as the Pistol is arguably already the most powerful starting weapon, something that was not appreciated when XComUtil was written. The High Explosive buff is downright unbalancing since it allows UFO outer hulls to be penetrated at the very start of the game, totally changing the tactics of the Battlescape in a way that the Alien AI is not prepared for, and can't respond to. If you do select this option, use it only for the Heavy Laser mod, and refrain from using Pistol autofire, and definitely refrain from using HE as an entry charge to blast holes in UFOs.

In TFTD this option gives Gauss weapons unlimited ammunition. There is still a running argument about whether Gauss weapons are worth bothering with (Skipping Gauss Weapons). So using this option might be justified. But clearly it still gives an advantage to XCom, at least until weapons better than Gauss are available. So if you want the game to be harder, don't use it.

Other Options To Avoid

• Automatically Screen for Psi Ability
• Fight All Battles In Daylight
• Fighter aircraft can carry troops / HWPs
• Skyranger can mount air to air weapons
• Troops have all-round visibility from inside transports

Actually these last three aren't even options, prior to XComUtil 9.6, they are defaults. Turning them off is hard - just don't use weapons on transports or troops/HWPs on fighters. The all round visibility is not such a big deal, but if you turn it off, you will make the game harder again.

Firepower Adjustment

Despites what it feels like in the early game, X-COM eventually gets access to extremely powerful weaponry that make all both ground and air battles too easy.

Avoid Heavy Plasmas

Don't equip the majority of your squad with Heavy Plasmas. If that sounds too easy, then don't use alien weapons at all.

Advanced Human Craft (Firestorm/Lightning/Avenger)

The Avenger is an awesome craft but it is very overpowered. So build only ONE, and only when you are going to Cydonia. Battleships suddenly become very tough if faced with Firestorms...

Or, to fully experience the helplessness of seeing alien Battleships flying unopposed through Earth's atmosphere, don't build any Firestorms or Lightnings.

Avoid Blaster Launchers

To put it simply: the weapons are too powerful and thus the temptation to overuse them too great. Completely destroying a map is fun at start but butchering the aliens gets boring after a while. Either do not use the weapons or only bring 1 on each mission.

Rank-based equipment

Only give the best stuff to officers. For example Squaddies have to use personal armors and laser rifles; rookies don't get armor at all. Advancing in ranks earns the privilege to use newest equipment. So Sergeants can use Power Suit, but not Flying Suit. Even better, only give Flying suit to your Commander. Of course, you never want to commit your most experienced troops to hazardous front line duties, so this creates extra challenge.

Tech levels

Limit yourself to certain "tech levels". Here's an example:

• Level 1: Coverall, genuine Earth equipment
• Level 2: Personal Armor, Laser weapons
• Level 3: Power Suit, light alien weaponry
• Level 4: Flying Suit, heavy alien weaponry

How does it work? Simply limit yourself to stopping at a certain level. Or limit yourself in the speed of advancement, i.e. one level per a half year, etc. The latter example would mean you won't get to use the best equipment for two years!!!

Alternatively, allow yourself access to only a few high-power research topics, under the grounds that they're so complex that understanding them fully takes years. (Exceptions are made for end-game requirements, of course). Research topics that are high-power (AKA game-breaking) would include anything associated with Psionics, Plasma Rifle, Heavy Plasma, Blaster Bomb, the advanced aircraft (in particular the Avenger), the Plasma Beam/FBL, Hovertanks, and the Power and Flying Suits.

Use Unfamiliar Weapons

Use weapons that you are not generally fond of using or are not comfortable using. Use them in greater quantities or outfit your entire team with them. This has the potential to not only make the game harder, but it may get you accustomed to how these weapons are best handled. Combine it with restrictions on plasma weapons for best results.

One excellent example is the standard Heavy Laser - not the XCOMUtil variant. It's a weapon that is often branded "useless" because it's not an ammo-less parallel of the Heavy Plasma.

Other examples include Heavy Cannons and tanks. In particular, unmodified tanks.

Ranged Base Accuracy

If you are using the Collectors Edition of the game, consider making use of Seb76's loader and activate the ranged base accuracy settings. This adds new rules to shooting so that weapons will only work as advertised under a certain range, depending on the class of the weapon. Beyond these ranges, the shots start to get wilder. So while they can still hit, the odds of them hitting are reduced.

For those with other editions and can not make use of the loader, you can artificially set the ranges yourself and pick the type of shots based on the distance between you and the target.

Extreme Weapon Scenarios

Test your machismo by going to ridiculous lengths or just to see how far you can get before combat is no longer viable with a uniform weapon set whereby you limit yourself to only one type, or class, of weapon throughout. In addition to making the weapon harder, it has the added benefit of getting you to appreciate both the benefits and limitations of the weapons.

Some ideas to get you started: Heavy Cannon and/or Autocannon. Basic Rifles only. Pistol type weapons only. Rocket Launchers only. Grenade type weapons only (note, may need an emergency ranged weapons for flyers). Consider also a pistol and grenade scenario.

A Rocket Launcher or Grenade campaign for example will have several effects. While it does make defeating enemies easy, it introduces several management twists to combat that you would not normally subject yourself to in great frequency. Like collateral damage management will be needed for each and every shot taken. Ammunition has to be strictly managed, from the item limit to its actual expenditure and portage. Loot recovery is more difficult so some blast zone management is required. Mind control and reaction fire become extremely hazardous.

If combined with several other challenges such as no-psi and no alien weapons, you may even have to abandon some battle if all ammunition is depleted. Even if it was going entirely in your favour.

If you plan to play through to the final mission, allow yourself the use of stun weapons for capture of all the necessary aliens.

Squad Management

Avoid Large Squads

Restrict your squad regarding soldiers and tanks. Never use more than 14 plane slots to bring units into a battlefield (the capacity of a Skyranger). The logic behind this is that you can easily outnumber the aliens, especially if you are facing small UFOs thus assuring victory. Also, smaller squads allow for quicker play (you don't have to move 26 units each turn) and they make your soldiers more memorable, since you'll remember more their heroic achievements (or stupid deaths).

Load up your Skyrangers with maximum HWPs

A variant of the preceding scenario, not quite so hard. Instead of bringing 14 units into a battle you'll get just 5 (3 HWPs + 2 Soldiers) or 8 (2 HWPs + 6 soldiers).

Commando Missions

Use as few men to complete ground missions as possible-without HWPs, of course. Stealth, patience, care and caution become the priority. Even two or three-man teams can be effective if used properly. The logic behind this is that either way, aliens are probably too busy carrying out their mission or repairing the UFO to notice the dropship approaching (as evidenced by the fact that if you go against psionic aliens, you are safe from psionic attacks as long as none of them sees you, adding an extra difficulty: you have to kill every alien from behind and with one shot so they won't turn around and see you). Plus, micromanaging a three-man team is easier than managing a fully loaded Avenger. You have the advantage of surprise, use it! Just make sure you try to get at least most of the aliens before Turn 20 comes around (when they automatically spot you).

Solo Missions

Iron Man

If you are confident in yourself, use only one soldier. Knowing when to retreat and switch weapons at the dropship is essential, but try not to get wounded. Without friends with medkits around, fatal wounds are truly fatal. Get your popcorn out people and enjoy the show!

Chuck Norris

Your best man, a rocket launcher, grenades, and an automatic rifle. Nothing invented before about 1970. A stun rod to simulate the devastating karate attack - watch out Aliens!

Bruce Lee

One man, one stun rod. (You might want to cheat and max out your stats first.) They won't stand a chance!

Bozo the Clown

One man, no weapons. And pray that either some aliens died during the crash or that they are stupid enough to hit one another with their weapons.

Large Squads

For those that are content with small squads between 4 - 8 soldiers, break the habit and take the opposite approach. Start using large squads. Hire a large qauntity of soldiers and fill the all available spaces on the transport. Rotate the entire team regularly so that there are no outstanding idividuals or superstars amongst the tea.

During the battle, keep the slogan "There's no I in Team" in mind all the time. Make every effort to send out the whole squad into the battlefield and that everyone gets some piece of the action. No more than 1 rear commanders if at all possible.

The difficulties introduced here include longer turns due to the increased coordination of the larger squad. Larger squads make bigger targets and increases the danger of friendly fire. When things do go wrong, the level of severity tends to be great, with the possibility of mass hysteria. Weapon by stat assignment may also be a problem with so many troops to handle and if you are in the regular habit of rotating the team.

If you find that this makes it too easy, consider dropping your weapon technology down a few notches.

Limited Miltary

Limit X-COM to a set number of soldiers per game. Not at one time, per game. So every soldier killed or sacked is an irreplaceable resource. The easiest version of this could be 250 soldiers, maybe rolling down to as few as fifty, depends on the masochism of the player. Optionally, to help a bit, start with maximum hires by editing the starting base, or allow those who want to can increase the physical stats of soldiers up to their caps in SOLDIER.DAT if wanted and can start with maximum hires. (Leave Psi alone!) This game is winnable, but increasingly hard as you decrease troops as every man lost is a critical resource you never get back.

The hard version of this is to try and complete the game with just the 8 soldiers you start with. It is possible to complete the game with just one soldier if you really want to make the game harder. You better hope that he has good Psi skills as you will not find out of the a few months. At least you'll have room for a 3 tanks on your skyranger.

Battlescape Time Limits

If you are used to playing the 'waiting game', pick up the pace. The Aliens aren't stupid. After 20 Turns in a UFO Ground Assault, they will take off again, leaving you empty handed (simulate this with a march back to the Transport, and Abort). After 20 Turns in a UFO Crash Recovery, the Engineers blow the reactor and destroy everything. Simulate this with a forced Abort on Turn 20, regardless of where everyone is at the time. Those who don't get airborne in the Transport are all missing or dead. Anything not hauled back to the Transport is lost.

Harder Economics

First of all, don't use any of the economics-related Exploits (see above). That really is cheating. For greater challenge in the strategic aspect of the game, try these scenarios:

Funding Council Income

Rely entirely on the Funding Nations to run your war. Details here.

Do not sell any alien equipment, corpses or UFO components. Do not sell manufactured items. Only genuine starting Earth technology (like Rifles or Avalanche Launchers) or researched aircraft (since they don't bring in money) may be sold. This makes it significantly harder. In February for example you have around $6,000,000 to cover base maintenance, wages, crafts, manufacturing and losses on the battlefield. This leaves not very much! Building new bases, hiring more engineers or just building a second laboratory is almost impossible. But it is definitely more fun than having worldwide radar coverage and 16 interceptors by the end of march.

No Commercial Manufacturing

Slightly less strict than Funding Council Income Only: don't manufacture anything for profit, as it's too easy to become largely independent of both the Funding Nations and the need to capture alien loot for cash. If you have any surplus manufactured material you don't want laying around, you have to build a warehouse for it somewhere.

No Laser Cannon Sales

An easier option than the previous scenario, but still quite a challenge if you are used to relying on Laser Cannon income. This will cut your income signficantly. Alternatively, play the XComUtil variant (see below) that makes Laser Cannons unprofitable (then you don't have to resist the temptation to cheat).

Limited Elerium

Elerium is incredibly valuable, probably the most important strategic material ever encountered by mankind. Much too valuable for the CFN to leave it in the hands of those crazy commandos who run X-Com! The CFN governments insist on keeping most or all of the Elerium for their own use. You goet to see what it's like defending civilisation without it.

50 Elerium Limit

You are limited to only 50 units of Elerium for the whole game. Any surplus must be "sold" - i.e. returned to the CFN for a fraction of its real value. Keep in mind you need at least 12 units to build your Avenger, otherwise you can't win the game.

Avenger Elerium Only

You are only allowed to keep enough Elerium to fuel one mission of your Avenger (12 units). Everything else must be handed back to the CFN. This means you can't build anything that requires Elerium. It also means you must scavenge all the parts for your Avenger from UFOs.

Mandatory Recycling

As above, plus you are required to immediately hand over to the CFN ("sell") any captured items containing Elerium (except for the specific parts you need to build your one Avenger). This is so the CFN can send them to a top-secret Elerium Reprocessing plant for extraction of the precious Elerium. You are allowed to start Research projects on them when you first return them to Base, but then you must immediately hand them over to the CFN. You are not allowed to use these items (except during the actual Battlescape mission when you capture them - and even then your troops have to lie about the ammo counts and pretend the aliens fired them).

This means you can never hold any Plasma or Fusion/Blaster weapons or tanks, no Psi Amps or Mind Probes, no Stun bombs, alien grenades, Power/Flying suits. You can build a Firestorm or Lightning, but there's no point, since you can't operate it (since that expends Elerium). You can't arm your craft with Plasma Beams or Fusion Balls. Lasers are your best weapons: in the air, on your tanks, and in the hands of your troops.

As a quirk, you can still build Plasma or Fusion defences for your Bases, since those don't appear to require any Elerium. As mentioned elsewhere, perhaps these are powered by a regular power station instead of Elerium.

(If playing TFTD, you are allowed to hold one copy of an item in Stores, if it is needed to be present for a Technology advancement, but then you must sell it as soon as it is no longer needed, and you must never use it in combat.)

Base Limitations

Base Defense

Don't play base defense missions. If your Base Defence weapons can't stop the Battleship, you have to abandon the base. This is because, actually, Base Defence is too easy and just an excuse to take lots of valuables off the Aliens, and maybe capture yourself a high ranking Alien to interrogate.

One Base

Build only a single base. This severely limits your efficiency, as you can only build a maximum of 35 base modules. Aircraft and radar coverage will be quite limited. Particularly challenging if combined with the scenario above!

For a real challenge...

Build that single base in Hawaii. See below under Scott Jones' scenarios.

Limit Base Size

You can build as many bases as you like but each base can only be 4x4 (or for the hard version 3x3, yes it is do able just very hard) instead of the normal 6x6. This version you will have to start a game and then edit you save game to make you first base smaller. Feel free to refund the cost of any modules and crafts you don’t have room for also if you don’t have room for a lab or workshop you might want to remove your Scientist or Engineer and refund there cost as well.

3x3 notes: No using XcomUtil to let you place troops in an intercepter, just because you dont have room for 2 hangers in any one base is no reson for making it easyer, This is ment to be hard if you want 2 crafts make 2 bases you start with more money then normal you should be able to build a second base right a way only 25 days till your hanger is built.

Earth Tech Modules Only

Don't build modules requiring alien tech, ie. Psi Lab, Hyperwave Decoder, Plasma/Fusion Defence, Grav Shield, Mind Shield. Laser Defence is OK.

Starting from Scratch - the No-Base Start

This scenario starts you off with no base, but with an ample amount of starting funds to get a minimal intercept/recovery base up and running. The goal is to obviously get the organization up and running from scratch with your starting funds and then attaining self sufficiency through selling captured equipment until you're back to playing to what you may consider to be a normal game.

To create this scenario, start a brand new game and sell everything, sack all staff and remove all base modules right down to the access lift. You will no longer have a base on the Geoscape, but the game will not think you've lost. From here, save the game. You will then need to edit your funds accordingly to how difficult you would like to make the scenario.

To set cash at a good level, some values to take into consideration include:

$550,000 (minimum) to $1,000,000(maximum) for access lift (varies by area)

$400,000 - living quarters

$150,000 - stores

$200,000 - hangar. $400, 000 for two

$500,000 - small radar or $800,000 for large radar

$500,000 - Skyranger hiring fee

$600,000 - Interceptor hiring fee

$60,000 - minimal misc armament allowance for one Inteceptor

$40,000 - Soldier hiring fee (allow for 8 to 10)

$500,000 - allowance for soldier armament

$500,000 - allowance for first month fees and misc expenses. Fees shouldn't be that hefty as everything will still be in-construction or en route to the base

A starting kitty of $5 million, which is on the more generous side, should be more than sufficient to build XCom up from nothing.

Once you've edited your funds, the scenario is ready to play. Before you start playing, consider making a backup of the save so that you can start a new no-base scenario again in the future.

The only downside to this scenario is that your first Skyranger and Interceptor will be numbered 2 and 3 respectively.

As an added challenge, you can also chose to combine this with the no-funding-country scenario by editing all the countries so that they've all withdrawn from funding X-COM. With this, you'll truly have to live off the spoils of war to survive.

1 Mission X-COM

A more hardline version of Funding Council Income Only, detailed here. In short, one Battleship mission, properly executed, can provide all the research needed to complete the game. The focus is on intercepting that Battleship and completing the game with only the spoils from that mission.

No Detection

Similar in concept to 1 Mission X-COM. No detection, and therefore no interception, of UFOs. Radar, airborne and hyperwave detection are ruled out. Almost as if the UFOs had some kind of stealth technology. This means no UFO Assault or UFO Crash Recovery missions. You are restricted to responding to Terror missions, Alien Base Assaults (when Alien Bases are detected by Agents only), and (possibly) Base Defence missions. This is quite hard as you get very little combat experience, artefacts or loot (and therefore very little cash). The Aliens also get a high score so many countries will defect. In fact, you cannot win this game, as there is no way to get UFO Navigations to build the Avenger. (Seb76's loader has 2 patches that do permit you to win: the "Roswell" UFO crashes option and an option where Base Control Tables don't explode.) More information here: Talk:UFO_Detection#Playing_With_No_Detection

Use XComUtil Features

XcomUtil is a game enhancer that was actually designed to make the game harder, although many of its features can be used the other way around.

XcuSetup configuration

When you run XcuSetup to install XComUtil a number of queries will be asked regarding which features you'll want to implement. The responses to the prompts given below will make the game harder.

• Do you want to use the improved starting base? (No)

With the improved starting base you start with an Alien Containment already built, your radar is upgraded and you'll start with additional scientists and engineers. It will also be designed to maximize defense. Mainly this is just to avoid boredom and frustration, but it is also an advantage.

• Do you want to use the alternate starting base? (No)

This retains the optimal defensive layout but doesn't add the extra facilities/personnel. Again, mainly to avoid frustration but if you say No you reduce your advantage and increase the challenge. At the very least you have the headache and expense of reorganising your base layout through construction and demolition.

• Do you want to use the improved Tanks/Weapons? (No to both)

You forgo having tracked tanks with the armour levels of advanced hover tanks, and slightly improved Pistols and Heavy Lasers. You also forgo a crucial advantage which is the ability to crack open UFO external hulls with High Explosive - you definitely don't want that if you are looking for a harder game!

• Do you want to use the new laser weapons? (Yes)

With this option chosen your lasers will require Elerium to be built (supposedly to act as power cells). This also prevents you from building plasma weapons (but not clips), thus preventing you from selling Plasma Pistols and Plasma Rifles since the aliens will stop using those. It also makes Laser Cannons and Fusion Launchers a lot less attractive to sell because of the time required to build them and the Elerium/Alien Alloys necessary for their construction. Be prepared for the blow on your finances...

• Do you want research help from captured aliens? (Yes! Yes! Yes!)

To make the game REALLY hard try this feature. First, it will increase the research times of most items tenfold or more, especially regarding the alien technologies. Instead of having to wait days or a week for a certain technology the time will increase to months. With a little bad luck you will be stuck to lasers and no armor when the Mutons and Ethereals start showing up. Second, the only way to speed research (other than having 250 scientists on all bases) is to capture live aliens, forcing you to bring a few Stun Rods for all missions. It is not required to have an Alien Containment present to receive the research help but remember it only reduces the time of the research being done at your starting base.

Scott Jones' Scenarios

Scott T Jones, the original maker of XcomUtil, placed some interesting scenarios on the XcomUtil site. You do not need XcomUtil to follow these scenarios, you just need self-discipline to stick to the rules. Here they are:

Xenophobe

Don't try to capture or interrogate any aliens, and sell all alien artifacts immediately. Don't build Alien Containment. You can not win this scenario in the normal sense, since you can never discover how go to Mars (or even that you need to go there). You simply play it until you don't want to play it any more.

Bean Counter

This scenario takes its name from the beaurocratic "bean counters" who drive us crazy with their constant cost cutting measures. You are not allowed to destroy anything, since that wastes profits. You are not allowed to shoot down any UFOs, since that destroys valuable artifacts that can be sold. You cannot use any explosives or any weapon that uses a clip or ammunition, since those would have to be replaced. You are only allowed to use reusable items, like lasers, flares, stun rods, and psi-amps.

Explosive

Limit yourself to only explosive weapons. This scenario forces you to learn tactics that protect you from your own weapons. It is virtually the opposite of the Bean Counter scenario.

Photophobe

You must not fight any battle in full daylight. If you land at a battle and an aura of light isn't visible around your soldiers, you must leave immediately. This scenario is very interesting and teaches you how to fight at night. It is much harder to win, but it can still be won because it is dark on Mars.

Technophobe

Sack all of your scientists and engineers at the start of the game. You must sell all alien artifacts immediately. If you cannot buy the item, you cannot use it.

This scenario forces you to learn how to use conventional weapons against the aliens. You can not win this scenario in the normal sense, since you can never go to Mars. You simply play it until you don't want to play it any more.

Neo-Pacifist

You are a Pacifist and cannot directly take the life of any living thing, even an alien. You cannot shoot down any UFO, because aliens might be killed. You cannot use any weapon that can kill an alien, even via reaction fire. Aliens who die during interrogation or because of lack of space in the alien containment facility are someone else's problem, so your conscience is clear.

The only lethal weapons that you can use are grenades, but you must still give the aliens a chance to escape. In this way, the alien causes its own death. For example, an alien next to an armed explosive with a long fuse can save it self by moving away, while an alien next to an armed Proximity Grenade can save itself by not moving away.

Even with these restrictions, the game can still be won by mind controlling an alien on Mars and having him stand next to an armed Proximity Grenade which was placed next to the master brain. Once this is ready, you release your control and wait for the alien to move, ending the game.

Single-Base Hawaiian

Games where you only have one base are not that different from normal games, unless that base is located in Hawaii. This scenario is very difficult and requires a different strategy. The challenge is that you have almost no radar coverage over any significant land mass. You must keep Skyrangers constantly on patrol over areas that are likely to have alien activity. Since combat is rare, you can not afford to skip any battles. This scenario teaches you how to use the graphs to gather information about areas in which you have no radar.

No Skyrangers

This scenario takes away your large, long range troop carrier, the Skyranger. Ideally, you should also eliminate the Lightning and the Avenger (except for the assault on Mars). Ground operations are conducted only with the small numbers of Soldiers that XComUtil allows you to place on board Interceptors (6 troops or 1 HWP + 2 troops) or Firestorms (10 troops or 1 HWP + 6 troops). This is quite difficult because you do not have enough men to allow for mistakes and the short range of your ships forces you to miss some terror sites. (This requires at least version 6.0 of XcomUtil.)

Shootdown

This scenario is an even harder variation of the No Skyrangers scenario. It not only takes away your large, long range troop carrier, but it also demands that you shoot down every ship you assault. This is extremely difficult, because you almost never capture any Elerium from ships that have been shot down.

Aliens Own Earth

In this scenario you start the game as normal, but the Aliens are in a very dominant position with over 20 bases already established on Earth. Survival is extremely difficult! This scenario takes a bit of work to setup before you can play, but definitely poses a serious challenge.

Speed Run

See how fast you can complete the game! For a very strict challenge, the clock starts when you choose a difficulty, and ends when you shoot the Brain on Cydonia.

The current record seems to be 62:21 minutes, not including save/load time, by tbgox. Yes, that's JUST over an hour of playing. He's got the videos up on youtube showing how he did it too. Good lord. http://www.youtube.com/watch?v=0wo71zOr5aU

Limited save/Reload

Depending on how strict you want to be with yourself, you can ban in-battle saves, save only when you want to quit the game and get on with real life, or for the really hard core, no save/reload at all: finish the game in one sitting, possibly combining this with a Speed Run. For a smaller challenge, try to keep a tally of how many times you save and reload, and see if you can minimise this number.