Skyline

A block slides back and forth above your tower. Tap to drop it. Anything hanging past the edge snaps off and tumbles into the city below, so the tower gets thinner with every drop that isn't clean. Land one dead centre and you get a PERFECT: the block gets wider again, and chaining perfects pushes the bonus up.

Miss the tower completely and the run is over. That is the entire ruleset, and it's the sort of thing you play with one thumb while waiting for something.

Coins from perfects buy crates that unlock 12 crew members who ride the top of your tower, and XP unlocks four skylines to build against: Night, Sunset, Dawn and Storm. Controls: tap, click or press space. Best played in portrait on a phone.