If you are playing on a laptop with integrated graphics, the game often crashes on startup. You will likely need the Intel HD Graphics Bypass package (d3d9.dll) to trick the game into thinking you have a dedicated video card.

Fallout 3 famously struggles with CPUs that have more than two cores. You often need to edit the fallout.ini file: Find bUseThreadedAI=0 and change it to bUseThreadedAI=1 . Add the line iNumHWThreads=2 immediately below it.

This was the biggest hurdle for years. However, Bethesda updated the Steam and GOG versions to remove the GFWL requirement . If your zip file is an older backup, you may need a "GFWL Disabler" mod from Nexus Mods.