My accidental "magnum opus" of yore, Zen Dynamics is an action-packed 9-map partial conversion for ZDoom featuring a slew of new weapons. The tale places you in the metaphorical shoes of an experimental super-bio-soldier-dude who awakens just in time for the Second Invasion. Journey from Earth to Hell and back to unravel your purpose and the story behind the chaos caused by the UAC and Zen Dynamics corporations.
Zen is a rather strange project in retrospect, as it was never really meant to be what it was. The original project was a seven-map deal hastily assembled in two weeks from some Malcom Sailor map scraps (God bless!) and a lot of highly-unfortunate duct-tape code, but folks seemed to like it, so I expanded it to a fully-fledged project. It's all rather ancient by today's standards and the reloading code is a horrible, terrible hack (though in my defense, it was the first manual reloading system ever to be done in ZDoom), but some people still swear it's fun so it may be worth a try if you haven't yet.