Fill every square without a mirror with a ghost, a vampire or a zombie. The clues, the numbers round the grid edges, show how many monsters you see looking into the grid from there, along a row or column. Zombies are always visible; ghosts are only visible when reflected in at least one mirror; vampires are only visible when not reflected in any mirror. The counts at the top of the grid say how many ghosts, vampires and zombies it holds in all.
On a touch screen, a tap does what a click does, and a long press what a right-click does (more ways to right-click). A key the puzzle’s controls show as a button can be pressed there instead of on a keyboard.
To place a monster, click in a square to select it, then click the desired monster at the top or type the monster’s letter on the keyboard: G for a ghost, V for a vampire or Z for a zombie. To erase a monster, click to select a square and then press Backspace.
Right-click in a square and then type a letter to add or remove the monster as a pencil mark, indicating monsters that you think might go in that square. Press Fill marks among the puzzle’s controls to write in every pencil mark wherever nothing is placed and no mark is written yet. The M key does the same, on any board where M is not something you type. Marks you have narrowed are left alone, and pressing again never starts over: see Filling in all the pencil marks. Here every pencil mark is all three monsters, and once every empty square has marks the press does nothing more. Press A to switch between pictures and letters (also a preference). A square’s pencil marks are the monsters it can still hold, so Check & save flags a set of marks that leaves out the square’s real monster.
Left-click on a clue to mark it as done (gray it out), and left-click it again to unmark it. Keep the left button down and drag to do the same to every clue you pass over that looked the same as the first.
With the keyboard, the arrow keys move the selection around the grid. The keys 1, 2 and 3 work like G, V and Z, and E, 0, Space, Backspace and Delete all clear the square. Press Enter to switch between placing monsters and adding pencil marks. Pencil mode is sticky: once a right-click switches it on, it stays on wherever you click, until you right-click again. The Marks key is lit while it is on, and pressing the key also switches it. To have it last only until your next click, turn off Right-click toggles a sticky pencil mode (stays on until right-clicked again) in the preferences.
Hint explains the next step rather than simply making it. It reasons only from the clues, the mirrors, your monsters and your pencil marks, so it carries on from wherever you are, as long as none of your monsters is wrong and no square’s pencil marks leave out its real monster; if one does, it asks you to fix the highlighted mistakes first.
Its steps work on pencil marks, so if some empty square has none, its first step pencils every monster into each empty square that has no marks yet. You can do the same yourself by pressing Fill marks. A square you have already narrowed down keeps its marks.
The hint crosses out a monster for one of two reasons: a sightline’s two numbers leave no room for it in a square along that sightline, or the counts at the top show that all of that monster have already been placed. It fills a square when only one monster is left uncrossed there, or when exactly as many squares can still hold a monster as there are of that monster left to place.
Every hint is a deduction you could have made from what is on the board. On an Unreasonable board there may come a point where no deduction is left and the only way on is to try something and see whether it works — that is what the difficulty name means. The hint says so rather than guessing for you: save your position, try it, and undo if it breaks.
These parameters are available from the ‘Custom type…’ option on the ‘Type’ menu.