Your plane sweeps left-to-right across the skyline, dropping one row lower each pass. Tap to release a bomb — flatten every building before the plane scrapes a roof.
Tap anywhere on the screen to drop a bomb from the plane's current position. The bomb carries the plane's forward momentum, then accelerates downward with gravity, so plan ahead of the column you want to hit. Each bomb removes the topmost cell of the column it lands in. The plane wraps to the left edge after exiting right and descends one row each pass. The game ends the instant the plane's altitude meets a building roof — clear everything before that to win the round.
Lead the bomb with the plane. By the time the bomb reaches roof height it has slid forward by roughly its fall distance times the plane's horizontal speed over its descent time. Drop the bomb when the plane is one to two columns short of the target — releasing directly over a building usually overshoots.
Kill the tallest column first. The plane's descending altitude is the clock — your game over comes when any single building's roof touches the plane line. Two short buildings and one tall one mean the tall one alone decides when you die. Spend the first three or four passes hammering the tallest column down to roughly the height of its neighbors.
The end-edges are last-pass real estate. The plane crosses the left and right edges far less time per pass than the middle, since it wraps and re-enters at the edge but moves continuously through the middle. Save edge columns for late, when the plane's altitude is already low — you'll get cleaner shots when the plane appears right over them.
Don't spam bombs on an empty column. The cap is four bombs in flight and each costs nothing on a miss, but each one is also a moment you weren't aiming the next shot. Watch your bomb's trajectory and only release the next when you're confident the first will land — you'll waste fewer passes on doubled-up columns when the column to the right of your hit is still untouched.