Cascades you have witnessed. Notes stay unlocked between expeditions.
The tower is built bottom-up by trophic level: soil and plants at the base, apex predators at the crown. In real Jenga the top blocks are safe. In an ecosystem the crown can be holding everything else together.
Before each pull, guess how much ecosystem integrity you will lose over the next 40 years. Ripple is under 8% (or a gain), Wave is 8–18%, Avalanche is over 18%. Correct calls score bonus points and build a streak multiplier up to ×5.
Each stage sets a pull quota and a floor: integrity must stay above the red tick on the ring. Some stages also set a target you must reach by the end. Rewilds bring a lost species back. Hunches give a rough field estimate of a pull before you commit. Three stars per stage: survive, call well, and keep the valley healthy.
Blocks marked ✕ are invasive. They are not counted in integrity, and pulling one can make the valley healthier.
Blocks that glow and pulse amber are booming beyond what the valley can carry. Blocks that fade to grey are declining. Anything that drops below 15% of its normal population falls out of the tower. Watch the valley too: trees, herds, insects and the water all follow the numbers.
Tap a block to inspect it. Drag to turn the valley, pinch to zoom. The pause button sits top right; the speed button next to it slows the cascade to 0.75× or 0.5×. Volumes, screen shake, slow mode, reduced motion, colour-blind colours and text size are in Settings, on the title screen and in the pause menu. With a keyboard: 1 2 3 call and pull, H hunch, R rewild, Space skip ahead, P pause, Esc deselect.
A simplified food-web simulation inspired by published research on trophic cascades in Yellowstone, the Serengeti, the Arctic and the Everglades. Effect sizes are illustrative, and real ecologists still debate how strong some of these links are.