You can add The Universim to your steam library by using the same key that you’ll use for game activation, but you’ll not be able to launch the game via Steam until the game will be available for purchase on Steam. This is Steam policy, we can’t let you play game on steam if we’re not selling it on Steam. By purchasing The Universim right now you’ll get access to the game immediately and you’ll be able to play it via steam when released.