RAASTA

How to play

• The classic rules. The dispenser shows your next five pipe pieces. Tap any empty square to lay the front one — you can't turn it, so think where it fits. A dry pipe can be replaced (it costs 50). When the countdown runs out the flow leaves the brass tap and runs through your road. Every pipe it fills scores 50; running through both ways of a cross scores 500. When it reaches a dead end the level is over — reach the distance and you go on. Each level the flow comes sooner and runs faster.
• The music. Every pipe is a chord, written as a Roman numeral in G: I is G, IV is C, V is D, ii is Am, vi is Em. The flow plays your road as a progression, one chord per pipe. Tonic chords feel like home, subdominants move away, the dominant (V) is tension that wants to go home to I — or, as a surprise, to vi. Pipe a V into anything else and its F# hangs there, sour: that joint leaks. A leaking pipe doesn't count toward the distance and costs 100.
• Bonuses. I–IV–V–I, I–vi–IV–V, ii–V–I, the plagal “Amen” IV–I, the Andalusian cadence in E minor (Em–D–C–B — E minor shares G major's key signature) and all twelve bars of the blues in G.
• Ears, in four levels. Hear the road's progression first. Then each piece plays its chord as it reaches the front of the dispenser. Most of the time it is the chord your road needs next — but listen for the strays: lay a stray somewhere out of the way, or the pipe leaks. I, IV and V first; then ii and vi; then E minor; then the 12-bar blues.
• Who. Just me, level after level. Same device: everyone takes turns on the same three levels with the same pieces. Online room: the same pieces on everyone's phone, a race for score.