I'm not trying to be a bitch and tell you what you have to do (since this is also some kind of showcase/art exchange thread for everyone I hope/guess) but here I my favourite (indie)-games, btw. (mostly pixel-art-wise)
+ Cave Story
+ Knytt Stories
+ Dwarf Story (comeon! Some injokes, please!
Screenshots should be awesome, so I can tell people: "Well that's lava and thats a small Dwarf. Oh yeah, and thats a megabeast. In a cage."
+ Shadow of the Colossus (not indie. but still indie. it's actually so unindie (sony studio) it's indie again.)
+ Metal Gear Solid 3 (mostly the comic-like minimal-colour-portraits etc.
+ Fez (but just because I like the pixel art and the white clouds fitting perfectly onto a sky-blue shirt :D maybe I should I even try that myself :D )
+ Solstice (NES) Super Mario Bros. 1/3 (NES) Zelda (NES)
+ Metroid and Super Metroid. (NES/SNES)
+ Tetris (GB)
+ Pokemon Blue (GB) (hell yeah, please
+ Geometry Wars Retro Evolved
+ Team Fortress 2 (!)
+ Half Life 2 - ep2
+ The Elder Scrolls 3: Morrowind
+ Monkey Island (1-3)
+ Crash Bandicoot
+ Final Fantasy 1-11 (but not the anime-ish parts of them... maybe more like... original artwork by Yoshitaka Amano or something :D )
+ Halo 3 :D but rather something funny than those slightly to awful "patriotic" shots and banners the game series is known for.
+ or just surprise me
I hope I don't seem like an asshole posting that "list".
It's already awesome if you post something but one of those themes would cause awesome-overkill in me. :D
Why I ask you to help me with all this:
a.) I like it when I wear stuff other people designed... somehow it feels strange to self-design my own t-shirts and wear them every day.
b.) I like to give you people another opportunity to showcase an interesting type of art (t-shirt frontprint)
c.) I'm not really good with such things. :D