The co-op horror game Content Warning is the latest independent title to climb the charts on Steam, thanks in part to a promotion that made the game free-to-own for 24 hours.

Content Warning launched on April 1. The game is free until 9 AM PT / 12 PM ET on April 2, after which the game will revert to its base asking price of $8. Content Warning is a riff on Lethal Company, another smash hit co-op horror game. Like Lethal Company, it tasks players with exploring strange environments and completing objectives while running from terrifying creatures. The primary twist is that players are content creators, recording themselves exploring and fleeing from horrors. If they survive and return, they can upload their footage to the game's equivalent of YouTube, "SpookTube," for fame and fortune.