If you download Uncharted: Fortune Hunter for your iOS or Android device today, you will probably be able to stock up on some exclusive rewards for Uncharted 4: A Thief’s End‘s multiplayer mode before it launches next week.

This is a free-to-play game with some in-app currency microtransactions. It’s a top-down puzzle solver, featuring a more cartoon-like art style than what the console version of Uncharted offers up on the PlayStation 4.

Solve puzzles to earn keys. Use the keys to unlock chests. These chests have rewards, like costumes, gear and multiplayer boosters, that you can use in Uncharted 4: A Thief’s End. You’ll simply need to link the mobile game to your Facebook account.

So far, the reviews are decent enough. Users are noting crashes and loading time issues, but the actual gameplay seems to be faring positively.

While you’re waiting for Uncharted 4 to release next week, dig into our review right here.