Galaga

This is the gametechnical version of going back to kindergarten and wonder why everything seemed so large back then. (in oldschool, action, classics, shoot em up, flying, retro, shoot and space)

Play similar games:

RetroShoot Just press and hold you mousebutton and let your weapons do the talking. Powerups, endbosses...you know the deal.
Duck Hunt If you ever had a NES and you gamesoul hasn't been covered with NextGen-mud yet: you have to play this one.
Star Wings A nice Shoot-em-up with an amazingly high amount of PCK...