Walkthrough Guide on Jack Tube
Level 1: Plumbing 101
The visual prompts pretty much explain this one. Click yellow gems when they're within reach to collect them. Click platform edges to jump up to or down from them. Click the tube end to jump into it; you'll pop out of the other one. Jump into the exit portal by clicking it once you've got every gem and are close enough to it.
Level 2: Pills Here
Get the pill, then click on the enemy to shoot it dead from a safe distance. Each pill is good for one shot, and Jack can't miss. The tube ends are color-coded; the identically colored ones are connected. Once you're on the upper right, you can use the elevator as a shortcut back to the middle of the level.
Level 3: Speedy Thing Goes In...
This is the first level in which you have to perform what I like to call a "tube-jump": if you jump into a tube end from up high, your momentum will be conserved. Stand on the right side of the gap in the upper level (click in the middle of the gap to jump over it) and jump into the tube end down below from there to reach the upper right area.
Level 4: A Game of Squash
Push the block and you'll automatically toss it through the tube to crush the monster. Then push the block again so you'll have something to stand on to reach the rightmost diamond. The weird mushroom-like thing near the exit is a springboard; use it to reach the exit.
Level 5: Spring Cleaning
Remember, click in the middle of a horizontal gap to jump it. To reach the upper right, kill the monster, then jump onto the springboard from the upper ledge.
Level 6: Pyramidst
Toss the block through the tube, then push it off the edge to deal with the spiky enemy; you can then safely jump between the spikes by clicking in the middle. Forget what the last level told you: you can use the springboard from its level to get to the top level. Once there, push the glass block off the edge to break it and free the diamonds.
Level 7: Elevator Action
To get to the middle left, take the elevator from the top level, jump to the middle right, and then tube-jump using the darker tube ends. You can then toss the block through the tube, tube-jump back, and use the block to get rid of the spiky enemy. To get back to the lower level, use the elevator from the middle left.
Level 8: A Bridge Too Far
Tube-jump with the darker tube ends (jump into the lower one) to get to the upper level, then knock the black stick down to make a bridge. To return to the middle level, tube-jump back. Shoot the yellow monster from the middle level.
Level 9: Catty Pult
Get the pill, then shoot the yellow monster through the tube (yes, you can do that!). From the middle right, tube-jump into the darker tube end and watch what happens!
Level 10: Moving (Platform) Day
The button on the middle level moves the platform left and right. Tube-jump through the darker tube ends to get to the upper level (remember, jump into the lower one from up above). To take out the monster, get the platform on the left, push the block onto it, then hit the button to move the platform to the right; the block will fall off and squash the monster.
Level 11: Diamond Miner
Do not tube-jump or you'll hit your head on the spiky monster on the ceiling! Instead, kick the black stick into the tube, then jump into it normally from its level. To break the glass block, push the other block into it.
Level 12: Drain Cleaner
Before trying to get the pill, toss the block through the tube and use it to weigh down the other end of the black stick. The blue button opens the drainpipe and drains out the deadly red liquid. Don't forget to look inside the drainpipe for a gem (that's what the picture in the bottom middle means).
Level 13: King Me
The springboard at the beginning is safe to use when it's in the MIDDLE position. Before using the first tube, shoot the monster through it. Use the second pill to shoot the king before going through the second tube. Shoot him a second time with the third pill, then crush him with the block. You can then push the button to turn on the exit, then click the crown to use it.