A square in NetHack is a single space on the screen, in which a single ASCII character or tileset tile fits.
Each square can hold:
- One monster (including the player)
- One dungeon feature
- Up to 32,767 items
- One engraving
It is impossible to have two or more monsters or dungeon features on the same square, as is traditional for roguelikes, with the exception of the player riding a monster (e.g., a knight riding a horse).
However, there can be many items on a space, even if a monster, player or dungeon feature is also there. If multiple objects are on the same square, the symbol for the topmost object is shown. The order of objects in the pile can be seen using the look here command: [:]
The floor on each square has one of several terrain types (such as ice, moat, dirt), which affects how you move through and interact with it.
Inaccessible items[]
Sometimes an item (or several items) may appear in the same square as a wall or is embedded in rock. Traditionally there are only gems and gold pieces in rock, however it can also occur for any item if a monster carrying them has phasing or some other way of passing through rock or other impassable squares.
The symptom of stuck items is that you cannot move on to the square to pick up the items, unless you are polymorphed into a monster that can normally pass through walls. To gain access to these items you may:
- Kick the wall, which has a chance to cause the object(s) to come loose and fall off
- Dig with an appropriate digging tool or wand of digging to remove the rock around the object(s)
A slight variation on this is that some items are actually buried in the floor. These items are only found through the use of the detect treasure spell or drinking a potion of object detection, and when you move within sight of the item, it disappears. Digging a pit down, usually only available with a digging tool (as a wand of digging will create a hole, unless it is the special case of an undiggable-floor level) will reveal the item, similar to items found in a grave.