Nearly two years ago (in April 2010), I ported Brain Party to the N900 using javispedro's awesome SDL_gles library. Having nearly forgotten about it, I "ported" it to Harmattan today - It's even a bit easier with Harmattan's SDL, which includes the necessary changes. The game doesn't pause/silence when put into the background, but the basic functionalities work, including sound.
Download here: brainparty_0.5.91-3_armel.deb (39 MB)
Source here: brainparty_0.5.91-3.dsc / brainparty_0.5.91-3.tar.gz
The game itself has been written by Hudzilla Games, who also published the game for the iPhone and XBox 360 - if you like the game, you can support them by buying the game from there. This port is based on the open source version of the game.