Registration in the incentive game.

-_SpiriT_-
Try to activate in Uplay.

These stores (Stimpy, Stimpy, etc.) you are buying not the game itself, and the key to it. The instructions typically will specify what platforms you can enter this key, but because around steam is more hype than around other platforms, and product steam, respectively, more.

In General, Yes, you can buy the key to the game, but not the game itself, the game itself gives you have steam, if you activate the key (Or the origin of pleem, whichever key took), download and install this game from the steam servers and play. All just

-_SpiriT_-

First, try to enter the key again in steam, it is likely that you have entered is not correct

Second, as the same may be that the key is not you, and therefore, if I want to play it, try to activate in Uplay, Origin

Someone in this thread trouble recognizing sarcasm.