Major Nelson announced earlier today that a handful of games are half-off today-only on Xbox Live. Fez, Sonic Adventure 2, Rayman 3 HD, and Trine 2 all go down to 400 MS points, while Hell Yeah! and Mark of the Ninja are 600 and Rayman Origins is $10 on their Games on Demand store. Trine 2, Rayman 3, and Fez are excellent and must-buys at that price, but multi-platform owners may want to pick up Hell Yeah! on the PS3 given its PSN discounts on DLC if you’re a PS+ member.