I am ashamed to admit that I never played much of the original DOOM when it came out or in the decades since. When I saw the Voxel Doom project I downloaded it and decided to finally give the old classic an honest try.
Voxel Doom is a mod for GZDoom, the open source implementation of the DOOM engine, which runs natively on Linux. The mod replaces 2D characters and props from Doom with fully 3D voxel-based models, made possible by what I can only assume is witchcraft on the part of the mod developer, @cheelo. Here's a quick video of me doing the famous first mission. If you want to backseat and tell me where the shotgun is I will appreciate it.
The effect is actually quite subtle and does an amazing job at preserving the original feel of DOOM (as far as I can tell). So far my favourite enemies are the Pinkies. I love their vacant faces, snorting noises, and how they waddle towards you with the sincere intent to do violence. I won't show the dead Pinkie model but it's truly something to behold.
To play Voxel Doom you will need the original DOOM WAD file, which you can get from purchasing the game on your platform of choice. A quick note for those without drag-and-drop file managers: you can launch the mod with the command
gzdoom -file /path/to/cheello_voxels.zip