Hey, I just noticed that the "next wave indicator" seems to always say "20 x" but the actual wave has more than 20 tanks... (level 40). I think the tanks health might not be correctly indicated either.
Suggestion: (2) it would be nice to have some automatic trigger you could set (and adjust during the game) to send the next wave on some condition (when n% of the last wave has entered the map or been killed or when the bonus reaches +175) -- this would make "expert" much more manageable.
Suggestion: (1) some progress bar showing how much of the current wave(s) have already entered the map (one thin bar per active wave, showing in a different color how many were already killed would be nice)
With small bombs at maximum (radius and damage), just release ALL waves at once and bomb them all to heaven at some U-turn on the map (lots of clicks - just neet to get the right timing). The few that pass thru this you can finish with a few super towers placed after that. Easy expert on almost every level (incl. 40!).
 "mini Tower Defence (mTD)"){kind=icon}