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Staircases are Build mode objects which allow Sims to travel between different floors on residential or community lots. In The Sims, staircases are clickable; a player can click on a staircase and direct a Sim to go upstairs or go downstairs. In The Sims 2, staircases cannot be clicked.
A basic straight staircase is one square wide, five squares long on the lower level, and four squares long on the upper level. These spaces must be left clear both above and below. The first square on the lower level and the fourth square on the upper level is reserved for the landing, and players may place a floor covering on these squares.
The Sims
The Sims: Unleashed, The Sims: Superstar, The Sims 2: Apartment Life and The Sims 3: Generations add spiral staircases. They have a 2x2 footprint on both levels, along with an extra square on each level that's reserved for the landing. This saves space, and allows players to add upper floors to smaller houses.
A sweeping staircase for The Sims, which goes through a 90-degree curve from top to bottom and has a 4x3 footprint can be downloaded from SimEchoes. It was included in The Sims: Makin' Magic , which also included a wooden version. A reversed version of the wooden staircase is also available from SimEchoes, and a reversed version of the stone staircase can be downloaded from Reny's Sim Concept.
In The Sims: House Party, there is also the Anti-Heisenberg Teleporter, which serves the same purpose, but has a one-square footprint. Players with Unleashed or a compilation which includes it should note that dogs and cats cannot use this object or objects based on it.
In The Sims, only one Sim at a time can use a staircase. though there are hacked staircases that get around this. It is not unheard of for staircases in The Sims to get "stuck", and become unusable because the game considers them to be in use. The way to fix that is to use the move_objects cheat to delete the stairs, and then to buy new stairs.
The Sims 2
The Sims 2: Open for Business and The Sims 3: Late Night allow players to add elevators to lots.
In addition to the basic staircases, The Sims 2 adds modular stairs with matching side railings. Modular stairs can be used on uneven terrain at almost any height, though their normal height is the same as that of the foundation. Three modular stairs equals the height of one staircase. Modular stairs can also connect two floors in a building. To do this, leave a 1x4 space in the upper lever's floor. Place a modular stair so that it points into that space, and it will automatically extend down to the lower level.
In The Sims 2, several Sims can use a staircase at the same time, though there are still some limits. The basic rule is that one Sim can go up a staircase while another is going down it. The player can increase the number of Sims that can use a staircase at one time by placing staircases side-by-side. Staircases placed side-by-side will automatically connect, making a wider staircase. Modular stairs are somewhat different, because each section is considered a separate object. So, if modular stairs are used to connect two floors of a building, up to three Sims can go up (or down) them at the same time, as long as each one is on a different section.
The Sims 3
In The Sims 3, staircases are able to be any length the player wishes, and can have railing that is of a different style to the actual staircase. The railing can also be only on one side, unlike previous games. A tool in the staircase placing tool allows for multiple staircases to be placed side by side quickly and easily. Multiple sims can use the staircase, as in The Sims 3. The Sims 3: Generations also allows for spiral staircases to be used within the lot.
Custom Content
Staircases have often been modified by custom content creators. Sometimes, this is just a matter of redesigning them so they have a different appearance, such as making the Anti-Heisenberg Teleporter resemble an elevator rather than a science-fiction device, or making a staircase look like an escalator. At other times, staircases have been modified to produce working ladders or to be more-or-less working spiral staircases. Some custom staircases for The Sims and The Sims 2 effectively work as "vertical doors" or "teleportation pads" between floors, which allow players to simulate elevators.
Modified staircases for The Sims 2 may or may not be fully animated, and may or may not work well when used by pets.