-you will need the latest DirectX9 redist (download, run and unpack to a temp folder, open it and run dxsetup.exe) and VC++2008, the game will NOT run unless you have them installed.
-make sure the game is not installed in program files or windows if you are using vista or win7.
-careful when following FAQs, many of them are outdated. stick with this one or with those on systemshock.org, if you want to be safe.
also check here if you appreciate what the modding community has done.
GOG System Shock2 Mod spotlight (includes some extra mirrors for mods)
Setting up your System Shock2 install:
-patch up with ss2tool (5.1 or newer) this will make sure all the files are updated to their most recent version - some of the new mods require this, so do it before you start installing mods. just run the tool and point it to your SS2 install, everything else should be done automatically (you need to be connected to the internet, as the tool is a webinstaller). if you want to use the multiplayer, enable it in the options (it's buggy, you have been warned).
-run the game and see whether it works ok. if you have issues, check out the troubleshooting guide, and Useful links at the end of this post.
-see the mod guide on systemshock.org. you'll definitely want the strict/conservative ones:
SHTUP (hires object textures and fixes. you should install this one no matter how much of a purist you are) //mirror google docs
Four Hundred (hires world textures) //mirror google docs
Vurt's Space (hires space textures) //mirror google docs
SHMUP (better quality original music) //mirror google docs
Earth dynamic sky //mirror google docs (special install procedure - you will need to edit cam.cfg, and add enhanced_sky 1 into a new line)
highly recommended (but straying a bit from the original concepts) are:
Rebirth (AI models) //mirror google docs (don't forget the fixed earth.7z if you are NOT going to use ADaoB)
ADaoB (map/gameplay bugfixes. do note that you will have to start a new game after installing) //mirror google docs
ADaoB hires earth space (requires ADaoB, do NOT use without it) //mirror google docs
Tacticool (enhanced weapon models. if you use ADaOB, make sure to install Tacticool AFTER ADaOB) //mirror google docs
Cutscene Rebirth //mirror google docs (higher res intro animation)
-the mods are installed by unpacking the archive(s) into the DataPermMods folder (or, alternatively, DataTempMods). they must NOT reside inside their own separate folders (wrong setup, and proper setup). there will be some overwriting when you put multiple mods into the DataPermMods folder, just click yes when this happens. use of modmanagers is discouraged, as they are outdated/meant for version 2.3 and will not see some (new) mods. to remove mods, you will have to delete the content of those two folders.
-alternatively, you can try out the new modmanager (warning, still work-in-progress).
-enabling hud scaling
-enabling the windowed mode
-intel black screen fix
-last resort fix for those who cannot get the cutscenes working no matter what they try
-multimonitor fix (also try if your desktop resolution isn't listed in the video menu)
-optimus laptop fix
-discoloration and screen flashing fix
-audio issues fix
-there is a new version of openAL available here.
-multiplayer is buggy, and only recommend for patient veteran gamers. you should play the game alone at least once before attempting a co-op.
-there is a new shiny version of ADaoB currently in developement, it will include a ton of map and gameplay fixes, and also take advantage of NewDark's capabilities (such as 32bit lightmaps). follow this topic for updates (and hopefully, the first beta).
-save often, and make a lot of saves (13 slots are available, make a good use of them), so you won't lose too much progress when a save glitches out (still seem to happen for a few users, even with all the latest fixes).