Atari Jaguar
The final machine produced by the old Atari before their bankruptcy, this feline of a console is often remembered as one of the worst in video game history, its double-digit licensed game library being very much influenced by its difficult architecture of 3 CPUs, two being of a custom architecture even. Not to mention its questionable controller design, its late CD add-on that makes the thing look like a toilet, etc. Despite this, it ended up getting a fairly dedicated homebrew scene after its market life and its patents being released into the public domain, and although emulation left a lot to be desired for the longest time, BigPEmu more recently stepped in and took care of that, down to getting the CD addon emulated and even the unreleased VR unit.
I've always been rather interested in this thing, just from its notable unpopularity alone. I ended up playing some of the games when Atari 50 launched, including the ambitious-yet-obtuse Cybermorph, which feels like X/Lunar Chase and Star Fox combined, the genuinely amazing Tempest 2000 by the talented Jeff Minter (seriously you should go play this one), the charming Atari Karts, which I may just enjoy more than SNES Mario Kart, and Fight For Life, which I boot up to get a kick out of the intro sequence and not much else.
But the other really cool part of this system isn't even related to the games--the Jaguar CD allows you to feed your music into a Virtual Light Machine, also made by the aforementioned Jeff Minter, and influence the visualizations it produces through both the audio and the controller buttons. BigPEmu also supports this, down to letting you set the emulated CD to pick up from your device's audio, so you can put on something outside the program and have it effect the VLM inside of it. It's really neat! I sometimes use it over projectM in foobar2000 because that one can end up getting rather harsh on the eyes/not photosensitivity considerate. There's also a sort of charm to the lower-spec look from the system's limitations that give it some extra character of its own, where modern light synthesizers tend to go for the more "realistic" looks.
All-in-all, the Jaguar was very much a flop, but not one to be forgotten.