Before you make a purchasing decision, note that the Steam version of the game is more up to date than the GOG version, steam has more bug fixes and higher resolution. and even cool beta branches that add new features. only buy the GOG version if you care about DRM and Bonuses such as the game's soundtrack in both MP3 and FLAC. The manual both english and in russian. and some neat posters which are also in russian. TLDR: Steam version is better and is more updated, making the GOG version outdated.