My partner and I spent three years making our own 2D game engine and game as well: http://junkyardtom.com http://junkyardtom.com It took so long because we ini

My partner and I spent three years making our own 2D game engine and game as well: http://junkyardtom.com http://junkyardtom.com It took so long because we initially built it in ruby, but found it was too slow; then pascal but found out it wouldn't work so well on Android; then finally Java. It's also not a shoot-em-up -- there's a fair amount of logic involved in the movement of the actors (some rudimentary AI) and way too many game rules. Maybe we should have started with a shoot-em-up... We're going to release the engine some day (when we have time to clean it up) -- it uses XML files to configure all of the actors and the 'stage' so maybe it will be useful to teach basic parallelism to kids or something...