ATB Doom

ATB Doom, developed by Andy Bay, was among the first Doom source ports created for Windows after the Doom source code release in 1997. The port only saw a short development span and was quickly abandoned. Due to this it did not implement any notable new features, only offering bare-bones functionality and even lacking many standard Doom features such as networked multiplayer.

Early ZDoom versions adopted code from ATB Doom for its keyboard, mouse, and joystick functions.