Base Defence

Battleships

An inbound Battleship on a "Retaliation" mission guarantees a Base Defense mission for you is in the offing.

You can bring down these battleships with sufficient defensive installations, but the game is programmed to just send another on the exact same mission. It's been proven that about 6 or 7 Fusion Ball Defenses with Grav Shield (total defensive strength 6000) can hold off incoming battleships (hull strength 3000) indefinitely, but since you get no bonus (not even to monthly score) for blowing a battleship out of the sky, it's better to let them land eventually and just run the mission. Once you've run the mission, win or lose, the attacks stop coming. The aliens seem to forget where the base is...

BTW, only battleships actually assault your base, don't worry too much about other alien craft on "Retaliation" missions, they're just scouts. Shooting these down far away from your base may confuse the aliens as to where your base actually is.

Battle Tips

You really want everybody at home for a base defense mission. If you're caught with your Skyranger off at some UFO crash site, you'll have to defend the base with a rookie, two guys on crutches that were in med-bay, and the antique Tank/Cannon you hadn't got around to selling yet. Mind you, the odds are still in your favor.

Battleships will unload both regular aliens and their associated Terror Units. You won't ever see the battleship, but you will get to see all those nifty modules you've been constructing in the Base Planner view, close-up! Base modules have two levels. Soldiers will normally spawn/start in Living Quarters and Storage modules.

Base layout becomes quite important, as aliens can only come down into your base through hangars and the access lift. If you grouped your hangars with the access lift, then built one module only connecting to the access lift, that module becomes a choke point for base defense. A long chain of rooms becomes a long choke point ripe for mining with Proximity Grenades.

A soldier with a Motion Detector in an upstairs closet near the access lift combined with a rocket tank at standoff range will keep the aliens at bay until the rockets run out. -see also [Stewart's] strategy on xcomufo.com forums.

Blaster Bombs can clear your base in just a few turns, if you launch a few into the hangars and access lift. The problem, IMHO, is getting the program to supply your soldiers with blaster bombs instead of the various weird booty.

Corridors attaching to the right of a hangar come through a ground-level hangar door. Corridors attaching to the left don't get a door.

Doing too much damage to a room can also collapse it, and you will lose that room permanently. Any rooms that can only be accessed by going through the collapsed room will also be lost. Spawn-point rooms such as Living Quarters, Stores, Access Lift, and Hangars can't be collapsed.

You can recover lots of valuable Elerium-115 and alien weapons from a successful base defense. Losing or abandoning the battle means losing the base. Although sometimes you can still come out with a positive score for your trouble.

Bugs

Base defenses can be DEADLY.

But not for the reason you think.

The game has some totally funky system for deciding what equipment in your base will be available during base defence. (See '80-item Limit' in Known Bugs.) So, if you've been accumulating a lot of clips or mission specific special equipment, you might have *problems*.

Ie, make sure to sell unnecessary stuff before base defences. (You don't want to be armed with unresearched "Alien Artifacts".)

Also much feared is the dreaded "walled off section" bug. Sections of your base along the extreme south and east edges will often be separated from each other by dirt walls. Heavy plasma and blaster launchers needed in this scenario to excavate the dirt. Possible that heavy explosives might work too, I'm not sure. Soldiers spawning in Stores or Living Quarters here may be trapped for the duration.

Another ANNOYING bug I find is the dissapearing bodies and booty from aliens. This is related to the 80 item bug problem.

A much nicer bug is that HWP's automatically get a free load of ammo. Note you still need at least one soldier as aliens landing at an unguarded base - or a base defended only by HWP's - take it without a fight.

If you have a LOT of soldiers, enough to fill all your spawn points, soldiers will start taking alien spawn points. Which means less aliens. - much kudos to [Zombie]