This post is meant as a base for anyone wishing to mod the functions generating the initial base layout, something i wish to do myself as soon as i'll have some more free time. First of all, here's the code used to generate the base starting layout, the exavated spaces, the number and positions of steam vents and the starting facilities. The source is the XGBase class in XComStrategyGame.UPK Now let's go with a detailed Analysis: The scripts pouplates two bidimensional 5*7 arrays, one storing the terrain type and one storing any facility built on the tiles. Why 5*7 when the base has a 4*7 structure you might ask? We'll find out later! There are also two linear arrays, one used as a list of solid rock tiles for the random placement of Steam vents and one storing the position of the steam vents. First of all, the number of steam vents on the map is determined, by referencing the NUM_STARTING_STEAM_VENTS value we know from DefaultGameCore.INI. The actual number of steam vents generated is between 1 and (NUM_STARTING_STEAM_VENTS)+1 Before going further, we should also take a look at some excerpts from the XGGameData class in XComGame.UPK This shouls help us understend better what each tile/facility change means: After that, the m_arrTiles array is populated. This array stores the different types of terrain (see the XGGameData spoiler). This process also populates the arrDeepRockTiles array. The following is a summary of what is accomplished during those loops and how the process unfolds: The Y Coordinate starts at 0 for the upmost level, and increases up to 4 while going down. Since there's a level completely hidden from the player, the first visible level has Y=1 The upmost level is fully excavated (iType = 3) => "Addon_Excavated". Note that this is an "Hidden" level, wich is not displayed in the game. The second level is fully excavated This is actually the first "real" level. Each tile of the second level right side of the access lift (excluded) has a 75% chance to be restored to non-excavated state (iType = 0) => "Addon_SolidRock" The access lift tiles are excavated, while each other tile has a 20% to be a cave (iType = 2) => "Addon_Cave" Each solid rock tile from level 3 onward (Y>1, so from the visible level 2 onward) is also added to the arrDeepRockTiles array Next, the Steam vents are placed: Using the arrDeepRockTiles array, a random rock tile is selected and changed to a steam vent (iType = 1) => "Addon_ThermalCave" The same tile is added to the m_arrSteamTiles array, and removed from the arrDeepRockTiles array The process is looped untill the number of steam vents generated equals the valued determined earlier Then the facilities are built, by calling the SetFacility function. Here we notice thet the game uses an "invisible" facility level where the 0-space stuff is built: Facilities 2, 3 and 4 (Hangar, Mission control and Barracks) are built on level 0 (the "invisible" level) Facility 6 (AccessLift) is built on the first real level central position (3-1) Facility 9 (SmallRadar) is built on the first real level, next to the access lift (2-1) Obviously this is the satellite uplink On the appropriate difficulty, Facility 12 (OTS) is unlocked and built on the first real level, in the leftmost tile (0-1) Finally the UpdateTiles function is launched. This functon just double checks every tile, making sure every one is of the correct type.
