Originally Posted by metalcasket
According to Brad in either the TA preview or the latest podcast, the first 15 (yeah, it's the podcast
) levels or so are almost mockingly easy, but it picks up from there.
The first 15 (and more specifically the first ten) are mostly tutorial showing off basic game stuff like placing towers, harvesting, moving, rotating tower pieces, etc. Once we've eased you into a false sense of security, though things ramp up (especially by World 2).
We tried to make it challenging without being overly frustrating. Especially since we don't have IAP that could just let people work around the difficulty.