Ah, yes, you simply can't play anno 2070 through steam, it doesn't support it. This was supposed to be fixed ages ago, but recent updates to the game have messed with the fix. You have to play Anno through the Ubisoft launcher.
For me, that meant having to buy the game a second time, but I'm sure you can contact Ubisoft and work out something, even if it is just getting a refund off steam for a non-functional game.
mgunh1
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