Bloons Tower Defense 2 enjoyable, but a small suggestion...
If you're going to make bloons that can only be popped by darts/tacks, make them focus only on those bloons until there aren't any left/in range. I felt like those towers were pointless (even the hyper monkey) because they would target everything else. So all I did was make 5-6 bomb towers, maybe an ice tower or two in the beginning, and throw down road spikes. Either make the road spikes more expensive, or make the dart ones more useful.
Still fun though. :)
Chicken Chuck