Defendguin is a clone of William's classic arcade game, "Defender."
The mission is to defend little penguinoids from being captured
and mutated.

When you begin the game, your ship appears over some icy mountains
which are crawling with penguinoids (the good guys).  A number of
alien ships are flying around above the ground.  The game has a
radar display, UFOs, bombers, mines, pods, swarmers, baiters,
lasers, smart bombs, and more.

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