I just finished playing a very nice puzzle adventure I recently bought via the Humble Bundle 2/3. It’s called Machinarium and you have to help a little robot solve some riddles to get back to his beloved. Sounds cheeky but is very nicely done and made a lot of fun.
You can find the game and play a demo at http://machinarium.net/.
And of course it’s available for Windows, MacOS and Linux.