I have fond memories of playing this game in my 8th grade computer art class. I swear, that class was easy as hell. My friends and I could all do an A+ project in a day and spent the rest of the week playing Bloons. Man, I remember beating Bloons Tower Defense with only the standard monkeys. Having like 50 of them is awesome.
Anyway, back on topic, the game is apparently a shitty port, not to mention it's essentially a free game that's got a price tag on it (although N+ was essentially an addition to a free flash game, N). Not gonna bother.