ZDOOM is the DOOM we’ve all been playing for a really long time now.
Few even remember that the original release of DOOM was not full 3D. It was 2.5 dimensions. You couldn’t look up and down or jump. In fact, that’s where rocket-jumping came from, as it was the only way to go vertical.

ZDOOM was a backport of the z-axis code from Quake back into the DOOM engine. It enabled full 3D and dramatically enhanced the game. Carmack open-sourced DOOM code first, and then a couple years later Quake was open-sourced. The community did the rest.

I’m an old DOOMer. I’m gonna download this UZDOOM and give it a whirl.