Maybe you have tried it already: Tennix has been available for Maemo for quite some time now. The current version still has room for improvement (performance-wise), and the gameplay part runs a bit slow. That's why our team uses it as an optimization target for a course at the uni until the end of January.
Two benefits: You get a playable, fast tennis game for your tablets, and we get a bit more proficient in writing more efficient code and making better use of the current hardware. This will obviously also benefit the Desktop version of Tennix, as both use the same codebase.
I hope to be able to draw some conclusions and give you an overview of what we were able to do in a few weeks. Until now, try out Tennix and get used to its (relatively slow) speed, so that you feel the improvements when the optimized release is out :)