Grid Wars. Well, I can't speak for the PC version, but for Mac it's broken. The mouse controls aren't WASD. I can't go left with the keyboard controls and the thing is so old that it only has a PPC version available and hasn't been updated since.
Invaders isn't a Geometry wars knock off as the enemies have very little in common with GW. With the seed you give it, it generates the look of space invaders and uses it to determine what AI get assigned to a particular set of pixels. It also influences the ratios, so some seeds have more of a certain number of enemies types.
At higher levels of play the ratios become less of an issue than the power/aggravation of the enemies. The amount of real estate you can dodge into becomes ever less as your ability to keep the number under control decrease not from the numbers spawned, but some enemies like snakes are invincible outside of the weak spot and absorb shots harmlessly along the rest of the body. Then there are the beehives which upon death releases a swarm of angry Bytes which are fast, evasive, tracking and visually noisy making that much harder to track. I have yet to see all the types.
Power up are random and weighted, but some of the tweaks so far have been made so you get some thing as certain scores assuming you haven't gotten it. Power up also stack creating some very powerful combos. You only get one life, but can pick up shields, but they increase the size of our ship slightly and are limited to 2.
There is a frenzy mode you activate by filling a bar by playing dangerously. In frenzy mode time slows, firepower quadruples, scores double for a short time.
Having played Geometry Wars, Invaders feels "tighter". It's less herding enemies into black holes etc, more about killing them so you can live a couple of seconds longer.
Edit: HAHAHAHA now at 16,737,840 points in 23 minutes and 14 seconds