OBDATA.DAT is found in GEODATA and contains general information on objects found in the game, such as their accuracy and weight. It also contains template information regarding clip size; to hack dynamic Battlescape info on the number of rounds left in a particular item in play (or it's location etc), see OBPOS.DAT.
There are 80 records, each of which are 54 bytes long (a total of 4,320 bytes).
There are 33 entries for corpses (or otherwise destroyed robots and vehicles), four per large unit, one per small unit. Furthermore there are 41 "object" entries (weapons etc) and 6 obsolete/unused entries (mostly unusable, and without valid name pointers in the executable).
Values are presented in bold, according to the offsets in each record (0 to 53).
Note: If you hack OBDATA, you can have the game reload the data by entering or exiting the battlescape mode. This is true for the DOS version of X-Com (which switches between executables at these points), but the WinCE version may need to be entirely restarted.
0-19[0x0~0x13]: Name of object. Delimited by a null character. These are internal names... they all make sense, but are not the standardized names displayed in the game. Names and IDs (reference lookup numbers, including within OBDATA - see e.g.  to ):
|01/x01||PISTOL CLIP||28/x1C||empty||55/x37||Celatid Corpse|
|03/x03||RIFLE CLIP||30/x1E||empty||57/x39||Chryssalid Corpse|
|04/x04||HEAVY CANNON||31/x1F||CORPSE||58/x3A||reaper corpse 1|
|05/x05||CANNON AP-AMMO||32/x20||CORPSE & ARMOUR||59/x3B||reaper corpse 2|
|06/x06||CANNON HE-AMMO||33/x21||CORPSE & POWER SUIT||60/x3C||reaper corpse 3|
|07/x07||CANNON I-AMMO||34/x22||Heavy Plasma||61/x3D||reaper corpse 4|
|08/x08||AUTO-CANNON||35/x23||Heavy Plasma Clip||62/x3E||cyber 1|
|09/x09||AUTO-CANNON AP-AMMO||36/x24||Plasma Rifle||63/x3F||cyber 2|
|10/x0A||AUTO-CANNON HE-AMMO||37/x25||Plasma Rifle Clip||64/x40||cyber 3|
|11/x0B||AUTO-CANNON I-AMMO||38/x26||Plasma Pistol||65/x41||cyber 4|
|12/x0C||ROCKET LAUNCHER||39/x27||Plasma Pistol Clip||66/x42||secto 1|
|13/x0D||SMALL ROCKET||40/x28||BLASTER LAUNCHER||67/x43||secto 2|
|14/x0E||LARGE ROCKET||41/x29||BLASTER BOMB||68/x44||secto 3|
|15/x0F||INCENDIARY ROCKET||42/x2A||SMALL LAUNCHER||69/x45||secto 4|
|16/x10||LASER PISTOL||43/x2B||STUN MISSILE||70/x46||hover 1|
|17/x11||LASER GUN||44/x2C||ALIEN GRENADE||71/x47||hover 2|
|18/x12||HEAVY LASER||45/x2D||ELERIUM-115||72/x48||hover 3|
|19/x13||GRENADE||46/x2E||MIND PROBE||73/x49||hover 4|
|20/x14||SMOKE GRENADE||47/x2F||>>UNDEFINED <<||74/x4A||TANK1|
|21/x15||PROXIMITY GRENADE||48/x30||>> empty <<||75/x4B||TANK 2|
|22/x16||HIGH EXPLOSIVE||49/x31||>> empty <<||76/x4C||TANK 3|
|23/x17||MOTION SCANNER||50/x32||Sectoid Corpse||77/x4D||TANK 4|
|26/x1A||STUN ROD||53/x35||Muton Corpse|
The names as displayed in battle are stored in ENGLISH2.DAT, FRENCH2.DAT and GERMAN2.DAT, hence allowing them to appear in multiple languages. The exact pointers as to which item has which name are stored in TACTICAL.EXE.
20[0x14]: BIGOBS.PCK reference (pointer to graphic for inventory)
21[0x15]: FLOOROB.PCK reference (pointer to graphic for item on ground)
22[0x16]: Average Weapon Strength (Same as seen in UFOpaedia). For clip based weapons, this applies to the clip and not the weapon itself. Also note that if set to 0 the weapon will still "shoot" and the shot can still "hit", registering with the hit counter at UNITREF.DAT and making an easy way to avoid any damage while testing (if so desired).
Note that a (non-explosive) weapon will hit for between 0 and this*2 damage with each shot. For example, if you set it to 100, the weapon will deal between 0 and 200 points each time it is fired.
For information on hacking explosives vs. their blast diameters and strength, see this. It includes what happens if you change the Stun Bomb to HE.
23[0x17]: Display priority for when items are in a stack. The highest value here determines which will be rendered in the battlescape. In the case of a tie, the lowest ObPos record number wins.
24[0x18]: Inventory X Size (width)
25[0x19]: Inventory Y Size (height)
26-28[0x1A~1C]: Look-up within OBDATA for ammo this weapon uses. Up to three types possible; 255 for no (more) ammo. Note that ammo always directly follows its weapon in this file.
29[0x1D]: HANDOB.PCK Image of item when held in a units's hands in the battlescape view.
30[0x1E]: Often corresponds to 29, but does not appear to be used. Called "graphics type firing" by the game. Is this the shot graphic to use for the weapon?
31[0x1F]: Ammo Damage Type
0 AP 1 IN 2 HE 3 Laser 4 Plasma 5 Stun 6 Melee 7 Acid Spit (from Celatid) 255 Not Ammo
32[0x20]: Accuracy, Auto
33[0x21]: Accuracy, Snap
34[0x22]: Accuracy, Aimed
Percent TUs are rounded down (truncated). In an extreme case, if you hack UNITREF.DAT (Base TUs) to 199 and Percent TUs to 1, you will need 1 TU to fire the weapon (and can make 199 shots per turn). Or to really make things interesting, set Base TUs to 99 and Percent TUs to 1 - now it takes zero TUs! Also, it relies on Base TUs, not current TUs, so if you e.g. put Base TUs at 99, Percent TUs at 1 (0 TUs per shot), and Current TUs at 255, you still get 255 TUs, with 0 TUs per shot, for the turn you load that savegame - excellent if you plan on reloading it for each round of testing.
Don't set Percent TUs to 0. If you do, the object is no longer considered a weapon, and can only be thrown.
35[0x23]: Percent TUs Used, Auto
36[0x24]: Percent TUs Used, Snap
37[0x25]: Percent TUs Used, Aimed
38[0x26]: Primary use: Clip Size (for ammo; see ). Secondary use: Melee weapon strength, as follows:
0 All Corpses/Electroflare/Mind probe 8 Pistol 65 Stun Rod 10 Everything else...
Tertiary use: Turn detonation condition for "grenade" objects, but is otherwise unused. If the Grenade () and the 'is ammo?' () fields are set to true, this will create an explosive that is pre-armed to go off at a turn designated by this field. A side effect is that the grenade object will show an ammo count with this field's value.
39[0x27]: Melee damage type
0 AP 1 IN 2 HE 3 Laser or Gauss 4 Plasma or Sonic 5 Stun 6 TFTD vibroblade damage (does not appear to be used in UFO) 7 TFTD Electric damage (Bio Drone?)
40[0x28]: Melee Accuracy. Zombie found that changing this does not change the Stun Rod's 100% accuracy (nor does changing soldier Melee Accuracy). Thus the Stun Rod appears to be hard-wired to 100% for UFO, but in TFTD it is a valid and effective variable. (TFTD uses much more melee than UFO.)
0 All Corpses 0 Electroflare 0 Plasma Weapon Clips 100 Everything else...
41[0x29]: TU% cost when attacking as a melee weapon
50 Most objects 30 Stun rod 40 TFTD thermal tazer 10 Vibroblade 15 Thermal lance 20 Heavy thermal Lance 0 All Corpses 0 Electroflare 0 Plasma Weapon Clips
So a summary of 39 to 41 looks like this:
39 40 41 Objects 0 0 0 All Corpses/Plasma Pistol Clip 5 100 30 Stun Rod 8 0 0 Plasma Rifle Clip/Heavy Plasma Clip/Electroflare 9 100 50 Pistol/Pistol Clip 8 100 50 Everything else... (34 objects)
42[0x2A]: Explosive strength needed to destroy object. AKA "Constitution".
43[0x2B]: Item Weight, used for both throwing and encumbrance purposes.
44[0x2C]: Grenade Type
1 Standard explosive grenade 2 Proximity Grenade 3 Smoke Grenade 4-7 Gas - probably unused.
45[0x2D]: Value (or "priority") to the AI of picking up this weapon.
This field used as AI "worth to take" estimation flag, and only when it's >5. By accident or by design, it was not implemented. However this can be easily implemented by setting values above 5. This would have the benefit of making Aliens smarter after they lose their weapons or run out of ammo. See the talk section of this page: Talk:OBDATA.DAT#Field_0x2D_.2845.29
46[0x2E]: Boolean: Is Weapon That Shoots? (AKA Is Ranged Weapon)?
47[0x2F]: Boolean: Is Weapon? (AKA Close Combat Weapon)?
48[0x30]: Boolean: Is Non-Waypoint Weapon? (AKA Is Ranged Combat Weapon)?
49[0x31]: Boolean: Is Ammo?
50[0x32]: Boolean: Is Two-Handed Weapon? (AKA Is Large Weapon/Object)?
51[0x33]: Boolean: Is Blaster Launcher? (AKA Weapon Fires Guided Missile)?
52[0x34]: Boolean: Is Alien? (AKA Is Alien Artefact)?
53[0x35]: Scoring points (except for Elerium which works per 50 units). (AKA Victory Points for recovery).
Certain unique objects have "unique" features that are assigned to them. These are:
- Motion Scanner - can access motion scanner panel
- Medikit - brings up medikit panel
- Flare - will cast light around its object if on ground whenever the light level of the map is updated, such as when throwing a flare or when walking.
- Stun Rod - only weapon that can access its melee attack
- Mind Probe - can probe enemies
- Psi Amp - can access two different psi attacks
- Elerium - adds 50 units of elerium to storage at end of battle
TFTD's equivalents are same but also add the three drill weapons as melee weapons.
These properties are not configured in obdata.dat, but are instead defined by the game executable. Copying the stun rod info to a different record number results in an item which can't be used to zap things.
One way around the melee command limitation is to stack two or more items in your soldiers hands (via hacking) - The action menu will then display a combination of both items abilities. This allows you to bludgeon things with a plasma rifle (for example).
Laser weapons use no clips, but can still be fired. To give similar properties to other weapons you must remove their ammo type indexes (set offsets - to 255), give the weapon a valid damage type (set offset  to a value from 0-7), and give the weapon a power rating (set offset  to the average you want the weapon to deal). All the usual flags for standard firearms apply.
Grenades are similar to laser weapons in that the object's power (offset) and damage type (offset) must be set. In addition, to complete the object as a grenade, the Grenade type (offset) must also be set to standard (1), proximity (2) or smoke (3) in order for the item to be turned into an object that can be primed.
Be aware that regardless of the damage type entered, it will default to HE.
Any object that's not functioning as a gun or as ammo can be turned into a grenade of some description.
Note that if you set the Is Ammo? (offset) field to true, the grenade will be pre-armed at the start of the battle to explode after the turn specified in offset, which is normally used for ammo count or melee attack strength. The grenade will also gain an ammo-count display on it with the value in offset.
One practical application of this is to create exploding elerium pods that will explode after a pre-set number of turns. For example, setting offset to 40, and by the time you reach turn 20, any elerium pods that have not been destroyed or picked up will explode. Set the damage to strength to something insignificant like 1 to let them wink out of existence, or up to 255 for violent explosions.
The flag in Offset controls whether the object fires a way-point guided projectile. Projectiles fired by this weapon will also default to HE damage.
Once set, the flag overrides various obdata.dat settings. Firing costs will default to 60% while the accuracy of the projectile will not be influenced by the user's base accuracy.
- OBPOS.DAT - Stores positions of objects in a battlescape
- PRODUCT.DAT - Stores information on manufactuable items (Hours, Cost, etc.)
- PURCHASE.DAT - Stores buying and selling Information about most of these items
- UP.DAT - References items in this file for the UFOpaedia
- GEODATA - Parent Folder for file
- Saved Game Files