Radical Aces

Phenomenal 3D flight sim. It's impressive enough that you can get 3D graphics to run at this high speed in your browser - what's even cleverer is it's a flight simulator that's actually fun to play. You're given a range of futuristic aircraft (the EXA-1 Destroyer and E-9 Dragon Bird are particularly devastating) to defend a Martian colony against waves of alien planes and tanks invading from the from the planet "Zappor" (presumably because they were sick of all the other planets laughing at their unusual name?)

The flight controls are simple enough - left, right, climb and dive, though watch your height if you put your plane into too much of a roll. There's even an emergency "jump to light speed" option plus a pumping techno soundtrack - if there are criticisms, an altitude and damage indicator wouldn't have gone amiss (fly through the arch to recharge your abilities), and the whole thing takes a while to load but is frankly worth every second.

Arrow keys for left, right, climb, dive, Space to fire, + to accelerate, - to slow down, R for Radar, 1-5 change views, J to jump to "light speed".

In other violations of the laws of physics, your weapons include history's first ever homing laser beams (or "automatically giddied" as the instructions put it), and your ammunition doesn't seem to be limited, so fire away!