I was out...
On the 2nd level... water the tree so it grows and pops the bubbles? Weak. Not a great concept.
Also... firing the gun once with multiple shots counts as one shot... but if you click it one time, that also counts as one shot... Nah... that doesn't work.
I'm sorry you don't like the game. It's a puzzle game and I realise that a lot of players here prefer more arcade type themes - plus it was aimed at non-hardcore gamers so I guess some of you will find it too easy.
Watering grass to grow a tree? Make sense to me!
The 'gun' is a water pistol... pull the trigger and it costs a shot. I really can't see the problem?
but after a while it gets boring.