Shove Off: Arrow Puzzle

Tap an arrow and it slides until something stops it. Give it a clear way out and it flies off the board. That's level 1. By rush hour you'll be counting turns on your fingers. The whole game turns on trains. Park arrows of the same colour nose to tail and they couple, and from then on they move together: three cars sent one by one cost you three turns, while the same three sent as a train cost one, and every later level leans on that. Two slides make a turn. An exit ends it at once. New arrows show up early, drawn as dashed outlines with a number on them. Treat those cells as taken. A slide stops short of one, and an exit sails straight over it. Journey runs past a hundred levels, ten to a chapter, with a new trick in each chapter until crossings and rush hour turn up near the end, and after level 100 the chapters start mixing those tricks with an easy breather every so often. You clear…