You don’t need to own Rise of the Tomb Raider (our review) to take part in the game — you just need to tune into some livestreams on Twitch.

Developer Crystal Dynamics revealed details of how it has incorporated Twitch functionality into its latest game, which debuted today. Anyone playing Rise of the Tomb Raider in Expedition Mode can connect it to Twitch chat to enable viewers to vote on certain actions in the game. This primarily takes the form of viewers voting on which cards players will get to activate in the challenge modes. These cards can often help or hurt — although they are occasionally just silly. And while this should make for a more interesting time for the audience, Crystal Dynamics is likely also hoping it’ll translate into bigger sales for the game.

With built-in Twitch interaction and incentives, Crystal Dynamics and publisher Square Enix are attempting to court the video site’s mammoth audience along. Popularity with those viewers often translates into higher sales. More than 100 million people watch Twitch every month, and many of them are highly engaged with their favorite livestreamer. If the audience sees someone they like playing a game, it may push them into buying it as well.

Here’s a video explaining how it all works.

Examples of power-up cards include one that gives everyone a giant head or another that gives Lara a rainbow trail. My favorite is the one that sets Lara on fire, which she can use to ignite her enemies as well. That seems like a top-notch power-up.

In addition to the voting, Twitch members who use the Xbox One Twitch app to watch Rise of the Tomb Raider streams will get bonuses for their own adventures with Lara Croft. These are random items that’ll make your game a little easier or a little more fun — and they typically unlock when you do things like complete a side mission.