Forza codes are completely unused, and I haven't even taken the game out of its case.
Halo: MCC's codes have been used, but you get 100 multiplayer maps (oooooh) and all four campaigns in the main Halo saga (aaaahhhhhh). Experience 4-player split screen co-op and a fully remastered Halo 2: Campaign (woooooaaah).
Would rather sell than trade. I have way too many games right now.