A wineprefix is not a bottle, unless you're using Winebottler. Then you'll have to get rid of Winebottler or ask the Winebottler community instead, because this forum is for plain Wine. > 50,- EUR is a lot money to me so I like to play the demo first. It won't help solve your problem, but let me just state right now that apparently the demo is really not representative to the final game. Check out a Let's Play on YouTube instead. As for your problem... What's the terminal output? Do other 3D applications work?
