Swing on a vine, tap to let go, then tap again to grab the next vine. Don't hit the ground.
You start hanging from a vine that swings you back and forth like a pendulum. Tap anywhere on the screen to let go — your speed at the moment you release becomes your flight speed.
While flying, gravity pulls you down. New vines hang from the canopy ahead. Tap again when you're close to one to swing your arm and grab it. If you're too far the grab misses and you keep falling.
Let go too early and you don't have enough horizontal speed. Hold on too long past the bottom of the swing and gravity wastes your momentum. The best release is around the bottom of the forward swing, when the vine is roughly straight down and you're going fast.
The vines get further apart as you progress. Hitting the ground ends the run.
Goal: grab as many vines as you can.
The fastest point of any pendulum swing is the very bottom, where the vine hangs straight down. Releasing there gives you almost pure horizontal speed and zero wasted upward arc. Practice letting go a hair before vertical on the forward swing — that's where the vine is still gathering speed but your trajectory will already carry you outward and slightly down toward the next vine's reach.
Look ahead, not at your current vine. As soon as you release you should already know which spot the next vine occupies, because while in the air your only decision is when to tap for the grab. A late grab tap is a soft death — you'll slip past and gravity will finish the job — while a slightly early tap usually still snaps you on because the grab radius is forgiving. When in doubt, tap a beat early rather than a beat late.