Cross Runner

Run the lane, grab every stack of planks you can carry, and pick your door. Gates come in pairs and each one does something to your pile — one adds, one takes away, one doubles it, one halves it, and now and then one hands you keys instead.

There is always a right answer and never much time to find it, because the run does not slow down and a spiked barrier will take a third of everything you are carrying. Whatever you finish with becomes a staircase, one plank per step, and you climb it.

Every tenth step is a milestone slab that pays out, and every third milestone doubles its own payout on top. Ten steps is a modest return; forty is a tower.

The gems you bring back buy any of twenty-seven skins, or levels of the magnet that drags plank stacks across the lane toward you.