SpaceChem is a marvelous game. I don't know anything about chemistry, but I found it easy to follow the game's instructions for assembling atoms into molecules. The real challenge of the game is in programming a pair of robots that have to work in a constrained area. The free demo will give you at least a few hours of play time to decide whether you want to purchase the full game. I shelled out the $15 immediately after finishing the demo and haven't regretted it. Anyone who enjoys programming will have a good time with SpaceChem, and as the OP said, tinkering types should love it.