This is a good game for most of it, but whichever of you made the levels is clearly an amateur designer because you have no concept of a difficulty curve. For the first 19 levels of the game it's a walk in the park. On the levels where the computer has a slight advantage they have enough dumb tendencies to make the game childishly easy. Then comes level 20 and BAM! You can't win. The enemy has three times the amount of stuff you do, and they use them to reinforce their defenses and overrun yours to an effective enough degree as to make the level impossible. You have wasted my time and I hate you.