Prism Axis

Prism Axis puts a living river delta in your hands. Drag your finger across the terrain to sculpt ridges and valleys, then open the floodgates and watch a real erosion engine carve channels, move sediment, and build a branching delta lobe — cell by cell, tick by tick — entirely on your device. At its core is a genuine numerical simulation: water routes downhill carrying suspended sediment, the streambed erodes where capacity exceeds load, sediment drops and accumulates in the sea basin, and slopes relax where gradients grow too steep. Every run is seeded and fully deterministic, so a saved journey replays from start to finish without storing a single grid snapshot. Explore nine hand-crafted starting basins — from Canyon Mouth to Atoll Shelf — or convert a photo from your camera roll into a heightmap and flood it. Track your basin with live cross-section profiles, time-series erosion charts, and a strata histogram. Milestone events flag channel avulsions and growing lobe thresholds as they happen. Unlock eight geomorphic landform observations — braided plains, oxbow lakes, incised canyons, and more — documented in a 16-entry illustrated almanac that explains the science behind what you are watching unfold. No accounts. No in-app purchases. No network required. Just terrain, water, and time.