You can press R (or whatever key you defined in the remap controls section of the options) to restart the current level. Or you can access a "Restart level" button from the pause menu.
I played this game when I was 6, and I was fine, I caught on to how to use the towers, I knew what powers they used, and I beat the game. I don't know why people are complaining when a 6 year old can figure out how to play in 2 minutes.
Hey... the game is messed up. The physics are gone. You can't place objects and the doll jumps through the ground... And whenever you hit a object on the doll, it freaks out and freezes. When you reset... it spawns with nothing.
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You can press R (or whatever key you defined in the remap controls section of the options) to restart the current level. Or you can access a "Restart level" button from the pause menu.