Adventure Time: Hey Ice King Why'd You Steal Our Garbage !? --- If you're a fan of the show then you NEED to get this game. It's pretty fun and the music is great, especially Marceline's theme.
Pushmo/ Pullbox: If you're wanting to play a good puzzle game then I would really recommend this one. You can also create your own Pushmo and share them with people/ Download other people's Pushmo with QR codes.
Cave Story: Its a really solid 2D, sidescrolling jump and shoot. Also has great music
Ghost Recon: Shadow Wars: This one is a top down view, turn based strategy game. It starts out pretty easy but gets pretty challenging later on. Based on what you said you were into I'd recomend this one the most