"Tux, of Math Command" ("TuxMath," for short) is an educational
math tutorial arcade game starring Tux, the Linux mascot.

Based on the classic arcade game "Missile Command," Commander Tux
must defend his cities from an attack. In this case, though, he
must do it by solving math problems.  Comets are crashing towards
the cities, and you must destroy them by solving their equations.

It has animated graphics, sound effects and music, and optional
on-screen input, for players who can't use a keyboard.

Homepage:
http://www.newbreedsoftware.com/tuxmath/
