Meet Amazing Alex - a creative kid who likes to make barmy contraptions out of toys and other things he finds lying about the house. In this physics-puzzler, it's your job to slot in the missing pieces to make his chain reactions come to life.

The fourth chapter is The Treehouse. These 32 stages take place in Alex's backyard getaway, and introduce a few new toys. We get to play with the bouncy ball, the remote control helicopter, and the zip wire.

If you get stuck, load up the level fresh and then recreate the setups shown in our screenshot walkthroughs. If you follow our advice to the letter, you'll beat the stage and unlock three stars on every level.

Level 1 - Angry Bird
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Level 2 - Giant Drop
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Level 3 - The Evil Dr. Pig
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Level 4 - Chopper Pilot
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Level 5 - Chopper Rescue
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Level 6 - Alarm!
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Level 7 - Ball Boy
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Level 8 - Bellhop
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Level 9 - The Great Escape
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Level 10 - Barking Dog
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Level 11 - Bellyful of Coins
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Level 12 - Ski Lift Sabotage
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Level 13 - Pirate's Puzzle
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Level 14 - High Jump
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Level 15 - Drag & Drop
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Level 16 - Skatepark
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Level 17 - Alien Escape
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Level 18 - Boing!
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Level 19 - Quantum of Mayhem
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Level 20 - The Dog Returns
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Level 21 - Bullseye!
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Level 22 - Refueled
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Level 23 - Mrs. Doll I Presume
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Level 24 - Pinball Machine
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Level 25 - Particle Accelerator
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Level 26 - The Ride Home
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Level 27 - Underworld
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Level 28 - Valet Parking
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Level 29 - Storm the Castle
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Level 30 - Oil Pipes
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Level 31 - Safe Landing
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Level 32 - Free Them All
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