Nice game.. Only thing that's really annoying is that you usually have to start all over again because it didn't save..
For all those of you having trouble with a map, try this:
Buy triple kick and dislocate knee.. If you meet an enemy triple kick (stun him) and continue kicking him until his knee is disclocated, then don't kill him and run towards the end, after you stunned 5 or 6 enemies no new ones will spawn, if you reached the end run back and kill them one by one. (yeah that's pretty much easy mode)
Nice game overall.. the air enemies are what really makes this game too tough at some points. I've tried Star Park about 10 times now.. it's just frustrating. Sometimes there are enemies flying from entry point route #2 to exit point route #3 which leaves no time to kill them, but even without these it's almost impossible to kill the flying ones and have a good defense vs. ground enemies.