At level 78, some panes appear pale and misty, with no colour showing. This is frosted glass. It hides its colour until you move it. The first time it glides, the frost clears with a little burst, and you see its real colour from then on.
The rules
- A frosted pane hides its colour until it moves. On the board it is drawn as pale frosted glass.
- Moving it thaws it. Any swipe that actually moves the pane clears the frost for the rest of that puzzle.
- It still follows every normal rule. Frosted glass glides, sticks, stops and blocks exactly like any other pane on its rail. Its colour still mixes in the real board state, even while hidden.
- The target picture is not frosted. The picture always shows the true colours of the finished window.
- Frosted glass always has to move. The puzzle maker only frosts panes that are not already in their final place, so you will always get to see every colour before you finish.
- A screen reader calls it "Frosted glass" until it thaws.
Working out the hidden colour
You can often know a frosted pane's colour before you move it, by reasoning from the picture. It is a lovely bit of detective work.
- Count colours. Look at the panes you can see and their shapes. Then look at the picture: every glass colour shown must come from some pane. If the picture has more yellow cells than the visible yellow panes can cover, the frosted pane is (or includes) yellow.
- Use the shape. A frosted L-shape or long bar must match an L-shaped or long run of its colour (alone or mixed) somewhere in the picture, on its own rail.
- Use the rail. A ↔ frosted pane stays in its row(s), and a ↕ pane stays in its column(s). Its colour must appear in the picture in those rows or columns.
- Use mixes. If a mixed cell needs magenta and the only pane that can reach it is frosted, the frosted pane is magenta.
Which pane to move first
Because frosted panes must move, they are often good first moves as long as the swipe is part of your plan. Moving a frosted pane early gives you more information. But don't swipe it just to peek. Every swipe counts, and the wrong swipe can cost a star.
A calmer approach: read the picture and work out the hidden colour first. If you are still unsure, choose a swipe that is likely to be useful whatever the colour, such as one that moves the pane toward its only possible target region.
Tip. The colour key in reading the target picture is extra helpful here: blue means cyan + magenta, green means cyan + yellow, red means magenta + yellow, and black means all three.
Frosted glass on the board vs in the picture
While a pane is frosted, the board looks different from what it really is, so you can't compare the board and the picture directly. The picture is the truth. Once every frosted pane has thawed, the board and the picture use exactly the same colours again, and the usual reading methods work.
Frost and mystery are never together
From level 95 you meet mystery pictures, which hide parts of the target instead of the glass. PaneSlide never puts frosted glass and a mystery picture on the same level. Hiding the glass and the answer at once would turn a puzzle into a guess, and every PaneSlide level is meant to be solved by reasoning.
Why frosted glass?
Most PaneSlide mechanics change how glass moves. Frosted glass changes what you know. It rewards careful reading of the picture, which is the core skill of the game. And the little burst when the frost clears is one of the nicest moments in the game.
Play from level 78 on the level map.