XCOM: Enemy Unknown features hand crafted maps, with a total of 68 maps, plus 3 additional ones from the Slingshot DLC, 71 maps into total. Out of these, 5 are slight variations on the same map (Europe/Asia versions and the Battleship), leaving a total of 66 individual maps (regular game + DLC).
In addition to the Battleship there are 5 other types of UFOs in the game, and each of these uses the same UFO interior but have completely different outside terrain and multiple deployment zones, making them separate maps. The only repetition of terrain features occurs on the Large Scout and Overseer UFO maps, where it appears only the UFO layout is different. If the Large Scout/Overseer maps are regarded as a variation on the same terrain, then there are 62 unique maps (EU + Slingshot).
In total, Enemy Unknown plus the Slingshot and Enemy Within DLCs feature a total of 115 maps, or 82 unique maps plus 33 variations (Battleship, Overseer, Europe/Asia, different starting areas and Covert Operations). For a breakdown on what maps are used on each Missions types, check Map Tables.
Despite the game mentioning: We're just north of the crash site, the UFO door/main entrance is considered to be North on the UFO map individual map pages due to the multiple Skyranger Drop Zones. On the other maps the Skyranger is considered to be North.
*SPOILERS* On the Starting Locations images the icons representing the starting locations of alien pods (on each specific UFO page) doesn't include the command pod usually located on the craft's bridge (Outsiders, Sectoid Commander and Ethereals, depending on game progression).
Enemy Within DLC
There are 44 new playable maps included in the Enemy Within DLC. These are broken down in:
- 14 entirely new maps;
- 6 new maps based on existing ones, 4 of the old ones can still be played on EW (Highway Construction, Office Paper, Fast Food and Street Overpass)
- 4 old maps with different starting areas (Research Outpost, Truck Stop, Convenience Store and Commercial Alley).
- The old versions are still included with the EW package but they have been deactivated for Abductions and can't be played during those missions. You can still start on the original locations of Truck Stop and Research Outpost during Council missions though.
- 20 Covert Operations maps (10 Covert Data Recovery and 10 Covert Extraction), that reuse both old and new maps by placing on them Encoders/Transmitters and/or EXALT Comm Arrays.
- EW has also completely removed the 2 Museum maps. On the Extraction mission (Thomas Hutch) it has been replaced by Street Hurricane Terror.
- The Council Extraction mission of Anna Sing (Boulevard Rescue) has been removed and replaced by Site Recon.
The older UFO and Abduction maps still present in Enemy Within have been slightly altered to place the possible locations for Meld canisters, or in some cases, like Street Overpass have been changed to give more starting locations with high Cover.
- Terrain (EU1994) - for details on the maps of the original game.