AIO Ultimate Patch for games make them playable without Steam. This application supports L4D2, L4D, TF2, Portal, Portal 2, GMod, CS:S, CS:GO, Dota 2, Insurgency, KF, DoD:S, NMRiH, Payday 2, Unturned, and many others. It also features a game version and update checker.
It replaces the original "SkyrimLauncher.exe" which is started by Steam
