Space Tripper for Mac

From PomPom:

Space tripper is a truly modern arcade shoot-em-up, combining the manic gameplay of classics such as defender, with a stunning state of the art 3D engine. Everything you would expect is here : Loads of ememies, big bosses, power-ups and a sore trigger finger!!

The gamplay is simple : Fly you spacecraft over enemy platforms, blasting everything in your path. Once each level has been cleared of all enemies, then you can progress to the next stage. Simple? ....then try it and see!
Be warned. This is one seriously tough shoot-em-up.