PDoom

PDoom, short for Phill's Doom, is a source port created in 1998 by Phill Harvey-Smith (Aurigae) based on DOSDoom v0.2. It received no further development past its initial v0.1 release. It features vertical collision detection (allowing to pass over or under monsters and other obstacles) and a few cheat codes allowing to enable or disable flight, to kill all monsters, or to get a quad damage powerup. It also treats the 2, 4, 6, and 8 keys from the numeric keypad as the arrow keys.