In my little free time I have recently been playing a new release on GOG, which got me dangerously hooked. Shenzhen I/O is a circuit/coding simulator (puzzle game). You have a circuit board, and some input and outputs, then you draw the circuits and write (simplified) assembly code to make the device work by the specification. The learning curve is pretty steep, and you have to read the manual to learn how the circuit devices work, as well as the assembly language. I spent six hours straight with this game when I first sat down with it. I just could not stop, the puzzles just become ever more interesting. There is a native Linux version on GOG, so I would warmly recommend this game to anyone with an interest in circuitry and coding.