There are just few commercial games for Linux and I don't have any reason to believe that this situation will change just because there will be perhaps a single digit millions of n900 (which will be obsoleted some month after release by a new incompatible hardware) users.

Commercial game companies have to make money and in this world, they have to protect their products from piracy so that some companies even build "copyright-protecting-devices" called game consoles.

I also have no reason to believe that Nokia will succeed to attract 3rd party developers this time after failing twice with n-gage.