A stone beam rests on a single pillar at the top of a mountain. You are standing on it. There is nothing underneath.
Boulders start falling from the sky. Every one that lands shifts the balance, and the beam tips toward the heavier side. Your body is the only counterweight you have, so you have to run uphill — toward the side that is rising — and hold the beam level with your own weight. The steeper it tilts, the harder it is to climb, and the more the rocks slide down on top of you.
Three kinds of rock, three different problems. Round boulders roll, so they never sit still, but they also roll straight off the ends and clear themselves away. Square blocks grip and stay, stacking into platforms you can jump onto for extra height. Triangles sit rock solid on their base, but nothing will stack on that point.
Get caught under a falling rock and you are pinned — you cannot jump until you dig out. Survive as long as you can. Every second scores, and every rock you shed off the beam scores more.
Real physics, no timers, no waiting. One run takes a minute. Beating your record takes longer.
Balance a sky-high seesaw as boulders fall — run to the rising side or fall.