GZDoom - ZDoom is a family of enhanced ports of the Doom engine for running on modern operating systems.
Chocolate Doom - Chocolate Doom is a Doom source port that accurately reproduces the experience of Doom as it was played in the 1990s.
Zandronum - Leading the way in newschool multiplayer Doom online.
Doomsday Engine - Doomsday Engine is a Doom / Heretic / Hexen port with enhanced graphics.
dhewm3 - dhewm 3 is a Doom 3 GPL source port, known to work on at least Windows, Linux, macOS and FreeBSD.
ECWolf - ECWolf is an advanced source port for Wolfenstein 3D, Spear of Destiny.