GameBASIC v1.1 - Released in 1991 by MR-Soft.  GameBASIC is an extension to Commodore 64 BASIC 2.0 designed for creating games.  Originally released in the German 64er magazine issue 73, I believe this is an updated version.  

Included in the archive is the original magazine article and an additional artice about programming with GameBASIC.  Both articles are in German. Also included is a game and demp written in GameBASIC.