Suggest you read the "Basic Guide to installing mods" wiki article; the "Environment" section in particular. Unlike other games you may be familiar with, XCom does not directly support modding the game. All mods (except edits to INI files) are "hacks" to the game executable. Steam then regards this as a "corrupted" copy of the game, and reinstalls, losing you all your mods. So you have to play XCom "offline" once you get it installed. Note there is a distinction between the "Steam Client" and a "Steam Game". The client updates fairly frequently, which is not a big deal as far as the game is concerned, except that it often results in resetting of the Steam settings for the game. So always check your game's "Steam Library" settings after a Client update.

As for what Bogdacutu means, all I can give you is an abstract interpretation. I am not a mod creator and haven't dealt with this before:

UPKUtils is a set of "command line" utilities for analyzing and patching uncompressed UPK files. Presumably "FixTOC" is one of those tools. I'm not familiar with the TOC file, but it most probably conforms to the general "UPK Format". The author of UPKUtils (wghost81) has also created a "UPK Format.pdf" file, which is available on the download page. The tool is for modifying a part of that format in the TOC file dealing with the compressed and uncompressed sizes of the "obb" files in question. Bogdacutu is saying his Android version of the tool currently requires that both the "obb" files involved in whatever customization is being undertaken must be extracted into the same folder, rather than being able to work on them still in the UPK file.

-Dubious-

Edited by dubiousintent, 05 June 2016 - 05:27 AM.