--- title: "How to play Ondulo: rules and a first game · SIWA" description: "Ondulo rules explained: probe an 8×8 field with waves to find 4 hidden modules, with a first game commented probe by probe to get you started." canonical_url: "https://dev.siwa.io/en/guides/comment-jouer-a-ondulo" last_updated: 2026-10-27 locale: en meta: "og:description": "Ondulo rules explained: probe an 8×8 field with waves to find 4 hidden modules, with a first game commented probe by probe to get you started." "og:image": "https://dev.siwa.io/og/en/ondulo.jpg?v=d89cc316" "og:image:alt": "Ondulo · Probe the field, find the hidden modules" "og:image:height": "630" "og:image:type": image/jpeg "og:image:width": "1200" "og:title": "How to play Ondulo: rules and a first game" "twitter:image": "https://dev.siwa.io/og/en/ondulo.jpg?v=d89cc316" "twitter:image:alt": "Ondulo · Probe the field, find the hidden modules" --- > Index of every page on this site: [llms.txt](https://dev.siwa.io/llms.txt) How to play # How to play Ondulo: rules and a first game To play Ondulo, send waves in from the edges of an 8×8 field: each wave comes out through another port, deflected and tinted by the modules it touches. From those signals, work out where the 4 hidden modules sit, whose shape and colour you already know, then submit your solution using as few probes as possible. Updated October 27, 2026 [Play Ondulo](https://play.dev.siwa.io/game/ondulo) ## Ondulo rules in 30 seconds Four **modules** are hidden in a field of **8×8 cells**. Below the field, a tray shows their shape and colour: all you have to find is where they are. There are four shapes: - the **large triangle**, filling a 3×3 square; - the **small triangle**, on 2×2 cells; - the **bar**, 3 cells long, horizontal or vertical; - the **diamond**, on 2×2 cells. To probe, tap an arrow on the edge, then tap it again or press the probe button. The wave crosses the field in a straight line and comes out through a port. The 32 ports are named after their edge: T at the top and B at the bottom, numbered 1 to 8 from left to right; L on the left and R on the right, numbered 1 to 8 from top to bottom. ## How do waves behave? A wave never passes through a module: it bounces off its faces. - A **straight face** (the side of a bar, the straight sides of a triangle) sends it back the way it came. - A **slanted face** (a triangle's hypotenuse, the sides of the diamond) turns it through a right angle. Each module the wave touches adds its colour, once. Red and blue make purple, red and yellow make orange, blue and yellow make green, all three make black. A white module deflects the wave without tinting it. The path is never drawn: you only see the entry, the exit and the colour. In the history, a wave that came back to where it started is marked as a return. Both ends of a known signal can no longer be probed: they would tell you nothing new. ## A first game, probe by probe Today's field holds a red bar, a blue diamond, a small yellow triangle and a large white triangle. Rows are numbered 1 to 8 from top to bottom, columns 1 to 8 from left to right. ### Probes 1 to 3: the red bar **T2** comes back red, then so does **T4**. Both waves travel down columns 2 and 4 and bounce off a straight red face. A vertical bar is only one cell wide: only a horizontal bar can span columns 2 to 4. **L2** comes back red as well: the bar sits on row 2, columns 2 to 4. ### Probes 4 and 5: the blue diamond **T6** comes out at **L3**, blue: the wave went down column 6, then turned left along row 3. **T7** comes out at **R3**, also blue, but heading right. Two neighbouring waves splitting apart on the same row give away the tip of the diamond: it fills columns 6 and 7, rows 3 and 4. ### Probes 6 to 9: the small yellow triangle **B2** comes back yellow, and so does **L7**: two straight yellow faces, one seen from below, the other from the left. So the triangle's right angle is in its bottom-left corner. **T1** goes straight through to **B1**, white: column 1 is clear, so the triangle starts in column 2. **L8** comes back, but white: row 8 belongs to another module. The yellow triangle fills columns 2 and 3, rows 6 and 7. ### Probes 10 and 11: the large white triangle **L8** has already revealed a straight white face on row 8. **R6** comes out at **B7** and **R8** at **B5**, both white: waves coming from the right are turned downwards by one slanted face, running from column 7, row 6, to column 5, row 8. That is the hypotenuse of the large triangle, whose right angle is top left: it fills columns 5 to 7, rows 6 to 8. ### Submitting All four modules are placed without overlapping, so the submit button becomes active. Correct on the first go, at a cost of 11. ## Placing and submitting: how does it work? To place a module, tap its chip, then a cell. Drag it to move it, and use the rotate or remove buttons once it is selected. A module takes up its whole square, even the empty half of a triangle: two overlapping modules turn red. Your solution is accepted if all 32 ports return exactly the same exits and colours as the real field. Two layouts the probes cannot tell apart are therefore both correct. ## How is the score calculated? The "Score" counter shows your cost: a probe is worth 1, a wrong submission 2. Lower is better. Up to a cost of 4, performance is at its maximum; each point beyond that takes off 5%, never dropping below 30%. Time does not count and there is no joker. In the game above, a cost of 11 keeps 65% of the performance. To do better, read our [Ondulo tips](https://dev.siwa.io/en/guides/astuces-ondulo). If you enjoy deducing a hidden code, [Mindo](https://dev.siwa.io/en/games/mindo) and our [beginner's guide to Mindo](https://dev.siwa.io/en/guides/comment-jouer-a-mindo) are waiting for you too. ## Frequently asked questions
How many modules do you have to find in Ondulo? Four, hidden in an 8×8 field. Their shape and colour are shown below the field; only their position and orientation are left to discover.
Does time count in Ondulo? No. The score depends only on the number of probes and wrong submissions. You can think for as long as you like before each probe.
What happens if I submit a wrong solution? A wrong submission adds 2 to your cost, like two probes, and does not tell you which modules are misplaced. You can fix your layout and submit again.
Is there a joker in Ondulo? No. Ondulo has no joker: probes are your only source of information about the field.
## Ready to play? Today's grid is waiting, free and without sign-up. [Play Ondulo](https://play.dev.siwa.io/game/ondulo) ## More guides [SSBPBODM

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