Submitted by twovests in killallgames
A very complete NES Mario reimplementation in LÖVE, bugs included, and a whole level editor before Super Mario Maker was a thing, and 4-player coop, and a ton of fun easter eggs.
This is a fun game to sink hours into, and as a bonus, all the source files are just... Right there. You can dick around with the code, change Mario's jump value, etc.
Oh, and the portals! A working portal gun, and a whole 2D Portal campaign.
This is a very cool game you should check out.