Vector Race is a computer version of that lecture time classic. Race around circuits you design by altering you cars movement vector every turn. Comes with a full track editor and AI opponent. THere's full instructions in the game but basically each turn you can alter your movement vector by 1 unit in each direction, to do this you can either click on the blue square or twiddle the number spinnres on the control panel.
Let me know if you design a cool track.