maybe u didn't read the tutorial, this frog have no attack but on RMB (right mouse button) it drops the bomb. U need just to blow up the wall. I hope u will see all content of game :)
hm, there is a rule after 3rd level: all enemies in the level must be dead, only then u will be able to move to next level. Drop the bomb, get out of frog body, and run away as a ghost, so bomb will kill a frog and blow up a wall.
