Do you know any good math games?

[*Laurelindo*]

I remember I used to play this math game a lot 12-13 years ago:

http://www.pedagogstockholm.se/PageF...72/Chefren.jpg

It was basically a series of rooms where you had to solve random math tasks, and there was also a 3D sequel inside Cheops' pyramid, which was a little harder - the problem is that these games have become too easy (I think the hardest questions are about trigonometry and algebra), so do you know anything similar that's one step harder?
My math skills are probably just marginally above average right now (like second derivatives, basic knowledge of imaginary numbers etc).