Machinarium

Escape the scrapyard - reassemble your body from the dumped parts, then use your extending torso and legs to climb out of the junk heap.

Enter Machinarium - solve the entry-bridge and gate puzzles to pass through the wall into the city.

Free yourself and your jail mates - make a cigarette (dried grass and toilet paper) to trade for a telescoping pole, drop pellets to make the guard slip and lose his key, then open your cell and the neighbours'.

Bring the dog to the lady - retrieve and repair the robotic dog and reunite it with its owner.

Mandatory, not optional. Win the five-in-a-row game against the robot at the oil pub in Lowtown - block him at three in a row, then set up multiple simultaneous open threats (a fork he can't block). A known trick: lose the first two games so the AI eases up on the third.

Help the musicians - assist the band as part of the town storyline (required to progress).

Flood the Blackhats - work the plumbing valves to flood out the Black Cap gang and clear your path.

Mandatory, not optional. Win both playable arcade cabinets: the Space-Invaders clone (score 1000+, shoot the red UFOs) and the Sokoban block-pusher (clear all five levels by pushing the small red block into the large one). Winning both gives you the coins you need.

Disable the bomb - defuse the Black Cap tower bomb via its disarm puzzle.

Repair the brain - fix the malfunctioning central computer near the end of the game.

Rescue Berta - free Josef's sweetheart, held near the top of the tower (the climax).

Escape Machinarium - complete the ending and leave the city together.