Ray Detective
A deduction puzzle. Three atoms hide in a box you can't see into. Send rays in from the edge and watch where — or whether — they come out, then mark where the atoms must be.
Fire rays into a sealed 6 × 6 box and deduce where its 3 hidden atoms are from how the rays come out.
FreeOn this device
Probes
Every numbered case can be pinned down exactly from the edge responses. In a free case, more than one arrangement may fit — any that answers every probe the same way is accepted. Cases solved: 0 of 12.
Controls
- Tap a point around the edge to fire a ray in from there; the result appears on the edge and in the probe list.
- Tap a box cell to mark or unmark a suspected atom. With the keyboard, move with the arrow keys and press Enter.
- Check tests your three marks. Start case again clears probes and marks; Free case deals a random box.
The rules
- An atom directly in front of a ray absorbs it (H). This is checked before anything else.
- Otherwise an atom diagonally ahead turns the ray away from it by 90°; atoms diagonally ahead on both sides send it straight back. The ray turns in place and the rules apply again.
- A ray deflected right at the edge comes straight back out (R). Matching numbers mark where a ray went in and came out; L means it loops forever.
Scoring, saving and limits
Fewer probes is better. A guess is accepted when its atoms would give exactly the same result for every one of the 24 edge points.
Your current case, probes, marks and solved cases are kept on this device only. Download a backup to move them.
The twelve numbered cases were chosen from all 7,140 possible arrangements so that each is the only one matching its edge responses. Free cases may have look-alikes, which also count as solved.
Questions
- Why did my ray come straight back?
- Either an atom was diagonally ahead right at the edge, or atoms sat diagonally ahead on both sides somewhere inside.
- Can two different arrangements both be right?
- In free cases, yes — if every probe would behave identically, there is no way to tell them apart, so both are accepted.
- Is there a penalty for checking a wrong guess?
- No. The number of checks is noted, but only probes count towards your result.