As we all know, Sierra was revived in 2014 by Activision Blizzard. It now focuses on re-releasing their old games, reviving their franchises and collaborating with independent developers for smaller projects.But SWAT4 in steam can not buy,,Markmod is not  the official server, By bringing SWAT 4 to Steam, people will be able to play the game online again as well as keep up to date with the latest patches.