A free-to-play version of Gotham City Impostors apparently launched very quietly on Steam yesterday. Monolith Productions' multiplayer shooter, originally released for Xbox Live Arcade, PlayStation Network, and PC in February as a paid-for download, is now available to download onto PCs for free. What's curious is there seems to be zero official word from Monolith or publisher Warner Bros. Interactive on the matter. What's more, the game appeared as an unofficial listing on Steam's Open Steamworks database earlier this week.

There are downloadable content packs listed on impostors' Steam page too, although the price list looks oddly incomplete. It very much seems the game launched accidentally, but it's definitely there. We're downloading it right now, and people are playing it.

We've reached out to Warner Bros. for comment.

[Thanks, Ethan]