Game won't load (Steam)

ERock4

I'm not sure what happened, but for the last two days, my game has refused to open. I click Play on Steam, and it goes through the usual deal of giving me the "Opening Marvel Puzzle Quest" window and my Steam icon turning green. Then that window disappears, and the game never opens. It switches from "Running" to "Syncing" on Steam, then my icon turns blue again and that's it. I'm not sure what's happened here. I've tried restarting Steam, restarting my computer, and even deleting the local data and reinstalling the game, but nothing works.

What do?