Planning
Don't rush into any level. View the entire screen and devise a strategy before you start moving around pieces. Having a clear plan can help you avoid foolish mistakes and save time. And remember, gravity affects wooden pieces and not just the bubble ball. Many pieces will fall down if not placed on a solid object, so keep that in mind when strategizing.
Level 18
One of the game's most difficult puzzles, Level 18 features the flag positioned in the bottom left corner of the screen behind a tall barrier. The pieces at your disposal include a metal beam, a wooden block and a wooden lever. First, angle the metal beam above the wall so its left end points down towards the flag. Next, sandwich the ball between the block and the lever, positioning the ball just to the right of center on the lever. Make sure to tilt the box so its lower left corner points up towards the metal beam. When you press the start button, the block, ball and lever fall to the ground, with the block smashing the ball against the lever and shooting it over the barrier, off the metal beam and down into the flag.
Level 20
Using the two speed power-ups can solve Level 20, which starts with the bubble ball perched on a suspended branch and the flag atop an elevated ramp on the far left of the screen. Place a wooden wedge at the base of the ramp, and then position a tilted steel beam to the right of the ball's starting point. Now, place one power-up on the ground in front of the wooden wedge and the other power-up midway up the ramp. Pressing start rolls the bubble ball into the metal beam, drops it into the first power-up, shoots it up the wooden block and into the second power-up, which propels it up the ramp and into the flag.
Level 21
The original game's final test, Level 21 places the checkered flag in a balcony in the screen's top right corner. Position the long wooden plank beneath the bubble ball and the wooden block above the bubble ball and shifted slightly to the left. Tilt the shorter plank so it angles up towards the balcony. Now, position the shorter plank so it's suspended as high as possible and farther right than the edge of the ground. Press start and the wooden block squashes the bubble ball against the long wooden plank. If timed properly, the ball squirts to the right and strikes the falling shorter plank, arcing over the balcony and into the flag.