Even first tutorial is laggy for me, i did find later the quality settings, set them to low but it made no difference. Phone gets hot, battery drains ect.
It might be nice to be able to remove a tower, although i dont think you should get a refund, maybe actually it costs additional to remove.
My current play style is to take the cheap turrets and place those down just as a maze then take expensive (sniper) and place it for best coverage over the maze, it could be interesting if the piece size was scaled with turret cost creating more need to plan ahead for placing key towers, furthering the puzzle aspect. Timer between waves could be a thing to
What happens when enemy gets to tree? I dont really see any change on screen.