Humble Bundle just launched its yearly Spring Sale. Between now and May 24, gamers can nab some deep discounts on AAA and indie PC titles while simultaneously donating money to a good cause.

It’s celebrating the start of the Spring Sale by giving away free copies of the indie roguelike survival game “The Flame in the Flood.” But it’s only available for a limited time. There’s just over 24 hours left to grab a copy.

A number of publishers are participating in the sale by offering discounts on back catalogs. Bethesda fans can get many of its recent titles at 50% off, including “Prey,” “Dishonored 2,” “The Evil Within 2,” and “Fallout 4.” From Software fans can get “Dark Souls 2” and “Dark Souls 3” 75% off in the Bandai Namco sale. The publisher is also cutting prices on some of its “Tales” and “Dragon Ball” games. “Total War” fans will want to check out the Sega publisher sale.

Bungie’s online shooter “Destiny 2” is currently $12 as part of Humble Bundle’s monthly subscription service, which sends a curated bundle of games to subscribers’ inboxes every month.

This year’s Spring Sale also includes a reward system. People will receive a stamp for every $5 they spend in the Humble Store or for visiting the store home page daily. If they collect one stamp, they’ll get a 7% discount coupon for city building survival game “Frostpunk” and a 10% discount coupon for the Humble Monthly subscription. Three stamps will get users a copy of the role-playing game “Millennium: A New Hope,” while five stamps will earn a copy of the horror puzzle game “Whispering Willows.” People have until May 17 at 10 a.m. PT to collect stamps and claim prizes. After that, a new week of rewards will begin.

Humble Bundle is a digital storefront for games, ebooks, software, and more. A portion of its revenue goes to charity organizations like Make-A-Wish, the American Red Cross, and GamesAid. It’s raised over $100 million since its launch in 2010.