Major Stryker is a 2D vertical scrolling shooter game for IBM PC, released in 1993 by Apogee Software (now 3D Realms). Originally the first episode of the game distributed as shareware, and the rest were issued commercially. The game was re-released as freeware on March 14, 2006. Like most such games the story is basically an Excuse Plot: in the wake of World War III, Earth is invaded by aliens called the Kretons. The hero of the war, Major Stryker, is sent through the wormhole they came through to strike back at their homeworlds.