Awesome 8 Bit / 16 Bit Games... like Cave Story+, Lone Survivor?

The Iconoclasts
You can download the alpha at The Iconoclasts alpha

Oniken!

Half-Minute Hero

if you're looking for cave story-like games, then you should check out Momodora and its 2 sequels. They are basically the poor man's Cave Story, which is hilarious since Cave Story is free. Well, so is Momodora...

FTL although I dont know if its either an 8-bit or 16-bit game

Castle In The Darkness, the game is on Greenlight, but not finished yet although there is a demo!

Retro City Rampage is pretty good. And it's full of 80/90's references.

Prison Architect.

AM2R

Dead Pixels, breath of death, home, hack slash loot, bit trip runner, terraria