Vertical Wind Tunnel

The Vertical Wind Tunnel is a recreational building that Duplicants can use to enjoy the sensation of high-powered wind through their hair. Beyond its morale function, it also behaves like a gas-moving device and can be used to transfer gas from one room to another. It has a priority of 4, so Duplicants will choose higher-priority recreation buildings first.

Mechanically, the structure is divided into four vertical sections from top to bottom: an upper pump, the tunnel itself, a floor tile, and a lower pump. The tunnel portion is effectively split into a central three-column area and two outer columns. When active, the center area contains gas, while the left and right sides are vacuum and help keep gas from escaping. Gas enters and leaves through the upper and lower pump areas, and the lower pump extracts gas from the five surrounding tiles in a manner similar to a Gas Pump.

The Vertical Wind Tunnel can operate even when the tiles above and below it are not gas, and it does not currently have an overpressure limit. This makes it useful as a gas transfer tool without the usual concern of a pump stopping from pressure buildup. In practice, it can be used to move gas between rooms while also serving as a recreational building.

A few edge cases are worth noting:

• If the 7th center tile from the bottom is non-solid and the 8th center tile is solid, the solid tile loses mass continuously, and the 6th through 7th tiles can become vacuum due to a bug.
• If the upper pump is blocked by a solid tile, the internal pressure rises slowly and appears to cap at a little over 200% of the initial value.
• If the lower pump is blocked by a solid tile, the internal pressure falls slowly and appears to bottom out at no less than about 50% of the initial value.
• If both the top and bottom are completely blocked by solid tiles, the building still functions normally, and its internal pressure stabilizes immediately at roughly 170% of its previous value.
• For this reason, fully sealing the top and bottom is recommended, since it prevents the building from stopping when airflow is poor or when the lower section would otherwise run short of gas.

In short, the Vertical Wind Tunnel is both a morale-building attraction and a specialized gas-moving structure, with unusual vacuum behavior and pressure handling that make it more flexible than a standard pump in some setups.