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Ondelu is a rheoscopic fluid simulator for iPhone. It recreates the physics of a shimmering liquid that responds to touch and the motion of your device — similar to a snow globe, but made of light.

Ondelu requires iOS 17 or later and an iPhone with a Metal-capable GPU (all iPhones from iPhone 6 onwards qualify). For the highest resolution simulation grid, an A14 chip or newer is recommended (iPhone 12 and later).

Open the app and start touching the screen — drag to stir, tap quickly for a ripple. Tilt your phone to watch gravity pull the pigments. Lay it flat and the fluid eventually settles on its own. Tap the settings icon (top right) to switch colour palettes.

Ondelu Plus is a one-time in-app purchase that unlocks seven additional colour palettes: Pearl, Copper, Lagoon, Gold, Rose, Ink, and Slick. There is no subscription — you pay once and own it forever.

In the settings sheet, tap "Restore Purchases". Make sure you're signed into the same Apple ID you used for the original purchase.

When the phone is completely still on a flat surface for a while, the simulation energy fades out. The moment you pick it up or touch the screen the fluid wakes up again — this is intentional behaviour. It mirrors how real rheoscopic fluid settles when undisturbed.

No. Ondelu is entirely local. It does not connect to the internet, send analytics, or require an account. See our Privacy Policy for full details.

Not at this time. Ondelu is built for iPhone and designed around the handheld experience of tilting and touching the device.