18Carolinas

General Information

Many rules are similar to 1825 (and 1860)
Companies are available in "tranches". Only when all shares of a company in one tranche have been bought will the next tranche become available.
Can sell president's share to market. Companies without a president are in receivership.
Yellow and Green tiles are double-sided. One side is standard gauge, the other side has the equivalent narrow gauge, or "Southern" gauge track.
There are special tiles for the "C" hexes, some of which have both gauges.
South Carolina hexes require "Southern" gauge track until Phase 5.
Routes cannot mix standard with Southern gauge.
When entering Phase 5, the "C" hexes are automatically upgraded to the brown "C" tiles.
After Phase 5, no new Southern track can be laid. Southern track tiles may be upgraded with normal gauge tiles. In addition, an entire route between two cities can be converted to normal gauge.
Trains and phases are completely different in 18Carolinas. Instead of buying specific trains, companies buy "train power" which can be allocated freely between trains for the purpose of running routes. For each phase, there is a "minimum" train size and a cost for each unit of train power purchased. Please see the rules for details.

In the "run routes" step there are buttons to increase (+Train) and decrease (-Train) the number of trains and buttons to increase (+Size) and decrease (-Size) the currently selected train size. Beware that when adding a train, the newly added train is not selected. The game will not allow increasing the size of a train if the current train power has been allocated (or over-allocated).
Note that depending on the current phase and the amount of train power a company has, it may not be possible to run more than one train.
After Phase 5, a new option is available in the "lay track" step: track conversion. Pressing the button switches the interface to track conversion mode to allow the player to select a route between two cities. Accepting the route will cause all track between the cities to be flipped to the "standard" track side, if possible. To revert to the normal lay track mode, use the "Undo" button.