18GA

General Information

Here are some highlights of rules in 18GA:

During the SR a player may buy a private company from another player, for any positive amount agreed upon. (§3.2.4.c.4)
Trains count towns for revenue but not for distance. (§4.2.3)
Montgomery and Tallahassee are open cities that cannot be tokened and do not block routes, track building, or token laying through them. (§4.2.3 i)
During Phase 2 and 3 corporations can only buy one train per OR from the bank. (§4.2.5 f)
If companies are purchased by corporations during Phase 3 and 4, the price is 50%-150% of face value. (§4.6)
Besides bankruptcy and bank broken, the game can also end if any corporation's market value reach $300. In case of bank broken or market value max the game ends in the current OR. (§5)
The Lexington Terminal and Waycross & Southern companies do not block any hexes. (Table III)

Augusta and Savannah starts as normal cities, but when upgrading to green they can only use their own tiles (453a and 454a respectively).
Brunswick and Macon starts as normal cities, and is upgraded using normal yellow and green cities. When upgrading to brown they can only use their own tiles (457a and 458a respectively).
If W&A upgrades Atlanta to yellow, the home token is returned to the corporation charter, and W&A can now put it out again, and select which city circle it should populate. This means that W&A can use whatever direction of expansion it wants, it is not restricted to south-west exit.
If some other corporation upgrades Atlanta without W&A having operated than the city that W&A will get as home city will not be selectable. It is highly recommended that W&A is the first to token Atlanta. When W&A does put out the yellow tile in Atlanta not that W&A now get the option to select which of the three city slots that it will use as start city. That means, W&A is not forced to use the one it was automatically located into when it started operating.
18xx.games does not support selling private companies between players, just buying. And as for other purchases from another player it is assumed that players have agreed in advance (via chat e.g.). A player that buy without agreement is breaking the game.