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 barebones funtionality 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.