The annual Summer Sale on GOG.com is kicking off by giving away System Shock 2 for free.

GOG.com has been growing in popularity in recent years, thanks in no small part to its support of DRM-free games and of course, The Witcher series. This morning, GOG is kicking off its annual Summer Sale.

Scheduled to run two weeks, the site claims that the sale will feature over 1,000 deals. Shoppers will gather XP for purchases that will unlock free games (including Spelunky and Gabriel Knight: Sins of the Fathers - 20th Anniversary Edition), and for the first 48 hours of the sale, you can get System Shock 2 absolutely free. The game is being given away as part of a stress test for GOG's client, GOG Galaxy. All you have to do to get the game is download the client, go to the sale, and claim your copy of the game.

Also as part of the sale, the Homeworld Remastered Collection is debuting DRM-free on GOG, with a 50% discount. GOG will also be streaming on Twitch for "GOG Plays on Twitch," challenging the GOG Community to play Stardew Valley and Grim Fandango Remastered for a community-wide XP boost.

The sale kicked off at 9 AM ET this morning, and the big day one special is The Witcher 3: Wild Hunt at 50 percent off. New deals will be added every 24 hours. The sale will end on Wednesday, June 22, at 8:59 AM ET.

You can check out all the deals at GOG.com.