Hedon took a different approach to the standard Doom formula. Sonic Robo Blast 2 kicks it to the curb completely, turning Doom into a 3D platformer and Sonic fan game. All the Sonic staples are accounted for, such as collecting rings, bouncing off springs, and collecting Chaos Emeralds in special stages. It’s crazy and even has a mod community of its own. One of the more notable releases is a kart racer game closer to Mario Kart than Sonic All-Stars Racing. Get it here and be sure to try out SRB2 Kart here.
Chex Quest is a relic from the early 90’s, and is a product of Doom modding before the source code was released. Offered for free in boxes of Chex cereal, the game is fundamentally a stand-alone Doom level pack with custom sounds and graphics. Gone is the blood and demonic imagery, replaced by corporate branding and a non-violent theme. Most surprising of all, it’s actually a pretty decent shooter. In fact, it’s so popular that there was a sequel and an unofficial third installment, as well as a new free game available on Steam. Get the original enhanced trilogy here.
Action Doom 2: Urban Brawl
This is basically Streets of Rage in 3D. Yes, really: someone managed to make Doom into a beat ’em up, complete with comic book graphics and quasi-realistic urban environments. Still, you get access to a small arsenal of devastating weapons. It’s slower-paced though, and some of the content is really offensive (think Pulp Fiction-style ironically trying way too hard to be edgy) but it’s good, silly fun that provokes a few laughs for its sheer absurdity. Punch your way over here to snag it.