Issues playing (getting to launch) downloaded game.

I'm not able to launch Horizon 2 on X1.

H2 along with Forza 5 are both downloaded on an external drive, and have been playing both games since November. Now, I can launch F5 just fine, but cannot get Horizon 2 to get into the game, every time I try to launch it the game just goes back to the main menu where all the apps show up, snap-in, play other games, etc.

I've tried unplugging the system (while turned off), restarting the console. Launching Horizon 2 while snapped-in, and still, nothing.

Any help, suggestions are greatly appreciated!

Delete it and download it again.