The Gatekeeper app for iPhone and iPad

In an epic showdown to determine your fate, the gatekeeper of hell has challenged you to a "game". One which no one has ever won.
If you do win you are awarded safe passage to heaven.
If you lose you will be damned, and subjected to an eternity in hell.

Tic-tac-toe has always been a popular example when studying artificial intelligence. It is impossible for a human to win against a machine without an infinite amount of draws (depending on the skill of the human player). Its a game that will have you re-playing forever, and one that anyone has played often enough to have become indifferent too.
Now re-invent it so that its exciting again. What context could you add to it that would make it entertaining, and repayable at the level that tic-tac-toe with a machine would demand of you?
The Gatekeeper is the result.
And yes, its possible. You can win.