I was playing that pretty hardcore for 2 months or so. My best is level 25, and I'm pretty confident the game ends after that but I just fuck up once or twice more than I can afford and run out of time.
proof:
There's lots of ways to play this. According to what you blow up first, the enemy gets different mutations and stuff. Pretty strategic really. One of the best abstract shooters so far.
If you wanna get some better scores, there's this trick. When shooting with the default weapon (non-guided), press left and right very rapidly with the 'slow' button pressed. This will in effect, keep you right where you stand, but the cone of the shots will dramatically get more concentrated. To explain what sort of effect this has, I can destroy the first iteration of the enemy in 5.5 seconds, best, using this trick.
If you reach level 10 and you don't have 300 seconds to spare (if I remember correctly), you're getting nowhere if you wanna finish this.
But beware of tendon damage to your directional keys arm. This isn't a joke. Almost messed up my arm with all the left/right pressing which is why I gave up on it too.
Also, I got to level 25 on this by basically destroying it head on for the first 5 stages, and then just bust it up a little sideways for two levels or so so it doesn't grow ALL in your face. After that, if you're quick and a bit lucky, in the first 5 seconds of each round you'll blow off the front pseudopods, getting a clear shot at the joints of the other two and eventually the core. It's simpler than it sounds.