Bring forth the Book of Armaments, it's time to learn how this works.
The Holy Hand Grenade isn't so much a game as it is a test of your reflexes. At the start, you can only play it once, and that play session lasts about three seconds (no more, no less), but as the days pass it has a tendency to become something of a habit. A horrible, horrible, stressful, amazing, Monty-Python-flavored habit.
Here's how it works: A grenade appears on the screen which you must touch and hold. As soon as the device is about to blow, you need to remove your finger as fast as possible. If your digit doesn't make it off the screen in time, you have failed. But you're not just competing against the clock, you're also in a massive tournament with all other players, and a new tournament begins each day.
On day two, you can enter a new tournament and -- if you succeeded the previous day -- play the second round of yesterday's tournament. Each day you progress in any given tournament, the time limits decrease, making it harder and harder until you eventually fail.
It's a cruel game and even the first round, which requires you to remove your finger in less than half a second, is no walk in the park. Thankfully, you are given the option to practice your technique without penalty in what amount to a training mode, but if your reflexes just aren't up to par, practice probably won't help all that much.
The game is brand new, and there are only a few dozen players entered in each day's tournament, so the chances of coming out on top are higher now than they will be in the future. If you hope to be crowned champion, your best bet is to get in early and play every day. The app is free, and it's got a good sense of humor and a great leaderboard system, so come compete with me and we'll see who comes out on top.