does somebody knows some good xbox 360 free games?

this is the most broke i have ever sounded.
but i traded my modded psp for my cousin's xbox 360.
i saw that as a win because not only he didn't use it that much, but because i never had an xbox.

turns out the reason he never used it so much is because he only had gears of war 3.
since my psp is modded, he can download any game and put it there without downloading anything else.
i wanted to mod the xbox too but like i need to buy some extra stuff for it (rgh).

but since i can't buy stuff rn because times are tough, idk what to do.
i don't want it to sit there and collect dust.

does somebody knows some good xbox 360 free games? (or can gift me some )

(i downloaded some demos, but still the only full game i have is gow3)