Xbox support has verified that the game is no longer available for purchase. He said I can get it back from Download History, but how does that explain the game being deleted from my console? He played it last night at about 5 p.m. and tried again this morning at 10. Between those times, it was removed.
Aside from that, I don't trust the Download History option. It is impossible to redownload the TMNT Turtles In Time game through that method. I'm assuming it'll be the same with this.
I just downloaded Turtles in Time just fine. Clearly the one who committed the crime...IS YOU!