played this in the beginning and it was too easy - then it was hard until I figured out what towers to use - level 7 was ridiculously easy - had it on automatic, fast speed and ended up with over $15,000 - now, level 8, seems completely impossible - maybe I just can't figure it out but the same towers do not work.
finally conquered level 10 - three each of pure red, white, yellow and blue in three different areas. a few teleports, instant deaths and confuse - then I kept adding more pure blue as fast as I could. ended up with 34 lives. great game, I'll miss it - 5/5