ATIPIX Mini Optical Mouse - think it came with one of these "universal office-on-travel" packs of connectibles and whatnots. It even has a retractable cable. USB of course.
The reason I use it is that it has the best trigger pull (sp?) of all computer mice I own.
This game is so simple from the mouse POV (left button, wheel) that I don't see any sense in investigating and investing further (I don't play anything else).