TF2 crafting minigame teaches you recipes (and makes you want to play TF2)
Team Fortress 2's loot drops crept in to my brain. At first, random items were enough. Then I had a stint of trading with friends. Then those friends became random internet men. Eventually I replaced "trade" with "buy" and "drops" with "purchases." I started buying hats and name tags and paint and... DAMN you Valve and your clever ways, exploiting my weak brain and its desire for virtual loot.
As highlighted by Reddit, this fan-made game uses your Team Fortress 2 crafting knowledge for good. You're tasked with creating rare stuff from an ever-expanding inventory. It's both educational and fun.
Don't know your Refined Metal from your Reclaimed Metal? Start here.