Over the past few months, the news that Sunset Overdrive is getting a PC port has been a terribly guarded secret. First it got rated by a Korean ratings board, then by the ESRB, and now it's even starting to get store listings.
A listing has popped up on SteamDB, which tracks new additions to the Steam Database, titled "SteamDB Unknown App 847370". However, a quick glance at the new addition quickly shows a piece of Sunset Overdrive header art, likely meaning the game is imminently hitting Steam.
Given the timing of the ESRB listing and this SteamDB listing, that this will likely be an "it's available right now" surprise announcement sometime soon.