Last Flower Defence

[Mistery]

A post-nuclear tower defense game in a world where there is only one last flower left. You must protect it no matter what!
The game features 35 easy waves, 60 hard waves, 25 different enemy units, 4 types of player units and 3 levels of upgrades per unit + special weapon/power-ups.

Play Here

[Mistery]

Started out on "Easy" but can't defend my flower too long My best so far was Level 16.
Guess I need to get the hang of it - but I'll have to go soon, will come back to it.
Hints are appreciated for successful strategies.

[Kzin]

Try upgrading...and build clusters....