Cordis
Valentine's Day 2013
Cordis is a Valentine's Day seasonal mod, created in early 2014 solely because nobody else had done it at the time. It has story, cutscenes, and an adventure-like portion, so those that prefer pure Doom might want to stay away. It's a bit rough around the edges because I ran out of time. The dialog is kind of cheesy, it's kind of linear and some of the maps are pretty drab.
It does, however, include some new weapons and enemies. For better or worse, it's pretty short at about an hour long.
Requires DOOM2. Freedoom works with some visual weirdness, you can play it with (Ultimate) Doom but there's a lot missing.
The Lite version is much smaller, but has a different soundtrack and fewer/lower quality graphics and sounds.