The developers made the launch announcement in their latest update video.
Introversion Software, creators of Prison Architect, have revealed that the game is due to be fully released in 2015.
News of a release this year comes from the latest alpha 29 update update video (made at about the 1:50 mark), which I've embedded for you below.
The developers also revealed that mobile version is in development too.
The game is still currently in alpha and available to buy through Steam's Early Access program. Take a look at the latest alpha 29 update video below to hear the announcement, and what the update brings to the game.
I've recently been playing Prison Architect, which is an extremely fun, and quite tough, game. If you're interested in buying it just head on over to the Steam Early Access page here. Remember, it's still in alpha, so expect bugs.