Level Zero

Each practice game builds a different set of rooms, with corridors, alcoves and more than one way through. Yellow wallpaper, a lit ceiling, and doors that stay shut until the maths is right.

• Walk with W, A, S and D. The arrow keys turn and move as well.
• Practice and today’s rooms begin in the office. Click the pile of floppy disks. Put the disks that match the note into the boxes. Leave out is for the ones that do not match.
• Click the view and move the mouse to look. On a phone, drag the right-hand side of the screen, and use the pad on the left to walk.
• Stand in front of a door and press E, or tap Door. A real door asks a question. Some doors do nothing.
• A wrong answer lets a tall black figure into the level. Each game it is a zero, a pi, or an up arrow. It may be in another room. The first time, it only follows for a moment. A second miss keeps it after you for longer, but on those first two it waits if you reach a door. After that, keep out of its way. It stands still while the exit code is on screen. You have 5 lives, or 3 on Hard. Each time it reaches you, you lose one.
• Chairs, cabinets, desks and other objects are tucked into the rooms. Four of them have a digit scrawled on them, and no room has more than one. The rest are blank. Some rooms are darker. One room turns red when you walk into it.
• At the way out, those objects are scratched beside the door. The note tells you what to do: the order, the reverse, a sum, a product, pairs of tens and units, or another rule. Then walk through.
• Easy, Medium and Hard change the size of the level and the maths. Today’s rooms are the same for everyone until midnight UK. Practice is a new map each time.
• The camera battery lasts 10 minutes from when the recording starts in the office. It keeps running while you sort disks and answer doors. When it is empty, the run is over.

Practice difficulty. Today’s rooms are always the medium layout.

Look sensitivity

A slow light pulse, under three times a second. Use this if flashing lights are a problem.

Some rooms have lights that cut out sharply, a little more than three times a second, across most of the view. Flashing like that can be a risk for photosensitive epilepsy.

Low flicker keeps a slow pulse instead, well under three times a second. It also turns off the quick flash when the figure reaches you, and the office-screen glitch.

• 0 Escapes
• 0 Runs started
• 0 Doors opened
• 0 Daily streak
• — Best easy
• — Best medium
• — Best hard
• — Best daily