Some would say Curse was the worst game on the console, but at least it's playable, unlike some other actual terrible games on the console.
I'd say Thunder Force and Wily Wars count as obscure.
Problem is we'd be here all day defining, redefining, and re-redefining the word obscure. It's rough because where else are you going to discuss these older games, but on the internet? However, no matter how many message boards, Youtube videos, etc., games getting better known on the internet, by the tens of thousands at best, aren't suddenly mainstream known.
I'd position Gunstar Heroes as obscure still, no matter how many top 10 Genesis game lists it makes. For a relatively mainstream series, I'd even suggest Metroid was fairly obscure. Seems like it holds onto the same barely over 1 million fans in an ever growing industry reaching billions(even if most of that is mobile gaming nowadays). No matter what it has for a fandom, Mother/Earthbound is definitely obscure. Most RPGs/RPG series are, including Chrono. Final Fantasy probably would be if it weren't for the few cases of heavily advertised millions sellers. (Hope it doesn't sound like I'm picking on Nintendo here, just some observations).
I don't want to rush anyone working on these, if there are any, but the games I'd love to see English translations for on this console:
Surging Aura - I know it's being worked on by Red Comet, if you can read French or Russian, you can already have a go at it. PSIV being a favorite, I want to see how they utilize it's engine with this one. Plus there aren't a whole hell of a lot of Arabic fantasy adventure/RPG's, though I can name 3 off the top of my head for this console alone(Beyond Oasis, Exile, and Monster World IV).
Sorcerian - The gameplay itself looks simple, but other aspects seem like they could be fairly complex. There's exclusive missions in this version as I understand it too.
Dyna Brothers/2 - Not much of a strategy person myself, but these 2 look like they could be fun.