The right way is (IMO) to have the chess engine in libraries, and allowing a UI client to use these. A UI client can be written in Qt or GTK or whatever.

I remember a really funny chess game called Battle Chess:



Depending on which type of piece was attacking which kind of other piece some kind of animation was shown. For example the bishop used magic, or the pawn used its lance to stick on the toes of the other piece, or the king would drink a potion. It was funny! And it got me into chess. Nowadays, on N900, such aspect would require nice artwork and OpenGLES, but maybe there is already a project like Battle Chess in existence?

Another important factor with games is that often they're not compatible with each other when running on different platforms. Which is cool on PyChess:

Also some kind of saving state of game I think is important, so you could play a move during your break on work and resume the rest next day. This is important in other interactive games as well, such as stuff like Boggle.

Just my 2 ct...