Rioni

run the line. the lamps know where trains go.

run down three tracks under the overhead line: swipe to change lane, jump, roll, grab the churchkhela, and read the switch lamps and the signals -- a train can only go where its rails go, so they tell you where it will be

Named for Rioni, the station where the ride that drew it ended; the Georgian for a railway, rkinigza (რკინიგზა), means iron road. A train cannot steer. Its wheels are flanged and coned so the rails hold it, and it can only change track where a switch, a set of points, has been thrown to send it across. So a railway always knows where each train will be: the switch in front of a train is set before the train gets there, a lamp beside it shows which way, and the signals over a track turn red when a train is coming down it. Anyone who reads those can tell where a train will be long before it arrives. The trains you can climb here are low flatcars and coal wagons on purpose: the wire over an electrified line is live, and climbing onto a carriage roof beneath it is how real train-surfers are killed.

Concepts: constraints, timing, decision-theory.

An interactive you play with one thumb, on Wundr.