Don't underestimate the power of level 3 lasers. Some slowing clouds and around 6 level 3 lasers can win the boss level, 2 level 3 lasers can take out 4 portals at a time. Nice game, quite addictive.
I hate the fact that the weapons you get are random. Once I had 5 hits and the other won hitting me once with a sniper, I never had one in the first place! It's too much luck for me. Also the crates could be a bit more evenly spread if it would be up to me.