Ask HN: Hacker-friendly Toys/Puzzles

I am a freelancer who works from home/coffee shop/etc. Recently, it has dawned on me that my productivity receives a good boost whenever I take small breaks from the task I'm working on and play; I have heard someone recently refer to this as "cognitive snacking".

I have been playing a few video games, but I'd love suggestions for puzzles or hacker-friendly "toys" that would let me take a break from staring a screen. So far I've thought of a Rubix cube or Lego Mindstorms, but would love the community's suggestions for additional (intellectually stimulating) distractions.