Tap to jump between two walls. Avoid the spikes. Climb as high as you can.
Your climber clings to one of the two walls. Tap the left half of the screen to jump to (or climb up) the left wall, and the right half for the right wall. Every move goes up one step.
Each step gives you +1 point and the camera follows you up. The walls have spikes pointing inward at various heights — land on a spike and the run ends, so pick the clean wall for every step.
You can't hang on forever: the bar at the top shows how long you can keep your grip. It starts at 1.5 seconds and gets shorter with every step, so read the spikes a few steps ahead and keep moving.
Read two or three steps ahead, not one. Each step up has at most one spike, on one wall, so there is always a clean wall to land on — runs end because the read came late, not because there was no way through. Before every tap, scan the next two or three steps so the following choice is already made when you land.
The spikes never move, and the picture scrolls only when you jump, by exactly one step. Waiting therefore changes nothing above you; it only drains your grip. The grip starts at 1.5 seconds and loses 5 milliseconds for every point: one second at 100, half a second at 200, and nothing left at 300. Use that time to read, then commit.
Tap once per landing. A jump takes about a fifth of a second and any tap made while you are in the air is ignored — a quick double or triple tap does not queue extra jumps, it just wastes the taps. And do not fall into a fixed rhythm: the chance of a spike on a new step starts at 30 percent and rises by 0.9 points per point scored, up to 78 percent from a score of about 54, so a tap-tap-tap pattern that worked low down walks straight into a spike higher up. Climbing the same wall again is also one step and just as good when the other side is spiked.