A rack of memory-metal strips, each one trained straight at the factory and bent out of shape before it went in. Press a finger on a strip to run the heater: once it climbs past that strip's own transition point it starts creeping back towards straight, and when it finally gets all the way home its pin drops into the mechanism with a click. Let go and it cools and bends right back, so babysitting one strip gets you nowhere - the whole rack has to be standing at the same moment before anything fires. Heat bleeds sideways into the strips you never meant to touch, and one that goes past its ceiling is ruined for good.
Alloy Memory Return is a casual game