Machinarium [Steam store page]
Nicely drawn point and click - but the puzzles are too obtuse for their own good. The hint button is hidden behind a long minigame with a key that shoots bullets (which the game doesn't mention and the minigame can't be completed without them)

Similar to Flow, but frustrating since you give up part of yourself to move - rather than being able to steer naturally. Later levels are mostly luck - the first 30 seconds determining whether you have any chance of completing the level

World of Goo [Steam store page]
I'm not madly in love with this game, but it's a decent way to pass the time. The puzzles are usually fairly easy, though sometimes it is hard to execute them because of the way the AI makes goo run around the structure

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