Bit Kid

I must say Chasm and Black Sun look a lot alike (perhaps due to the fact that they both are inspired by games like Castlevania and Super Metroid). If you guys have missed it by any chance, then you should go and give it a try. (I know you'll like it)
beware, it is a hard one

They do look quite similar. Chasm is just melee based and faster paced. Also underwater cave gameplay in an already slow paced game looks not so good.