How to play Blind Corners
A daily deduction puzzle: three new boxes every day, the same for everyone. A dark box hides a few mirrors. Fire a beam of light in from any edge and you learn one thing only: where it comes out. Every mirror it met on the way turned it around a corner you could not see. Mark where the mirrors must be, watch the beam run through your marks, and check when every beam is explained. Each beam costs a point, so find the mirrors in as few as the par, then share your result without spoiling the box. Missed a day? Every earlier day stays playable.
The rules
- The game opens on today's Easy box. The tabs above it, or the keys 1, 2 and 3, switch between Easy, Medium and Hard.
- Tap an arrow on the edge of the box to fire a beam in. It turns at every hidden mirror it meets, and the box shows only where it comes out: both ends get the same number and colour.
- Tap a square inside the box to mark a mirror: one tap for a slash, two for a backslash, three to clear it. Marks are free.
- The line on the box is the selected beam running through your marks. A port with a dashed red edge belongs to a beam your marks do not explain yet.
- Press Check (or K) once every beam is explained. If the mirrors are wrong, the box fires a beam that proves it, and that costs 2. Any layout that no beam could tell from the hidden one counts as solved.
- Every beam costs 1. Spend no more than the par, which is what the portal's own solver needed, for a star.
- With a keyboard: arrows or WASD move the cursor, Space fires from a port or marks a square, slash and backslash place a mirror, X clears your marks.
- Press Share (or C) to copy a spoiler-free result, and come back after midnight for the next three.
- Missed a day? The arrows beside the day on the title screen (or the comma and period keys) open every earlier day. Those do not count toward your streak.
A worked example
Say you fire a beam in from the left edge, row 2, and it exits from the top edge, column 3. The box lights up both ports with the same number and colour, telling you they are the two ends of one beam — but not which cells it turned in. A mirror anywhere along more than one possible path could produce that exact pair.
Fire a second beam from the top edge, column 2, next to the exit you already know. If it exits somewhere that is only possible when a mirror sits in one particular cell also consistent with the first beam, that cell is fixed: the two beams agree on nowhere else it could be.
Mark a mirror there — slash or backslash, whichever direction turns both beams the way they actually went — and the line the game draws through your marks should now retrace both beams to their real exits. If it does not, the orientation is wrong even though the position is right, and flipping the mark (a free tap) usually fixes it.
One tip for the par
Fire beams from ports next to ones you have already fired: two nearby entries that exit very differently almost always share a mirror between them, which pins one cell down using two beams instead of guessing from one.