Dr Robotnik's Ring Racers is a gorgeous free SNES-style arcade racer, built using Doom Legacy
Update: SNES stands for Saturn eNtertainment Electronic System, actually
I never expected to feel genuine affection for Dr Robotnik, whose various level-ending wrecking balls and spiked doodads have killed me a million times over, but here I am sobbing like a banshee over the release of Dr Robotnik's Ring Racers, a free Mario Kart-alike created by Kart Krew, the fangamer team behind Sonic Robo Blast 2 Kart, using the Doom Legacy source port.
It reinvents the good doctor as a benevolent patron of arcade motorsports, who has teamed up with erstwhile foe Tails to compress thousands of rings into a new energy source that, gosh, there's a lot of dialogue going on in this arcade racing game. But it's enjoyable dialogue - the intro frames customising the settings as rebooting Metal Sonic's brain - and it's not long before you're out on the course, motoring from checkpoint to checkpoint, and gathering rings that can be converted into boost. The visuals are a beguiling mixture of pure psychedelia and fidelity to the Mega Drive-era Sonic games. How about that trailer?
Ring Racers includes a Grand Prix mode with CPU drivers and several difficulty levels, and a Time Attack mode with replays. There's splitscreen multiplayer for up to four, and online play for up to 16, with characters including headliners such as the Blue Blur himself and rival Knuckles together with old nasties such as Buzz Bomber, and also-runners like Nack the Weasel, aka Fang the Hunter.
It runs on Mac and Windows, and they're working on bringing it to Linux and Steam Deck, too. Find download links and installation instructions over here. The file weighs in at around 600 MB. I'm sure you can find space for that. Do it for the Eggman.
Update 26th April 2024: As has been pointed out to me overnight by a thousand helpful, furious strangers, describing a Sega fangame (one with Saturn button prompts, no less) as "SNES-style" is a crime deserving of imprisonment in the deepest depths of the Labyrinth Zone. Speaking as a former Genesis/Mega Drive diehard, I can only hang my head.