Played: Machinarium
Not the first time I’ve started playing it, but probably (I’m not sure) the first time I’ve finished it. Machinarium is a game that probably reformed my attitude towards walkthroughs - completing the game is really difficult without them, not least because there are one or two infuriating pixel-hunts that are a little problematic.
You get the impression that they sensed this, though - there are beautiful hand-drawn walkthroughs for each level built into the game, behind a mini-game of their own, and they solve what could be a huge problem. Aside from that, the music is spellbinding, the art is consistently incredible and the story - despite being a highly-embellished damsel in distress outline - is sweet and often surprisingly funny.
I was playing on iPad this time around, and you can pick that up here. You can also play an online demo and pick up the full game here. And you really should.