There are various settings that the Worlds and mobile versions of Rail Rush can be played in.
Selecting a WorldEdit
In the Worlds version, the player clicks on the left or right arrows to select the world they want to play in, and then clicks on the "Play" button to choose it. The selected world must be unlocked. (See the footnotes below to learn more.)
In the mobile version, the player swipes left or right to select the world they want to play in and then taps the "Play" button to choose it. For premium worlds, there is an option to buy the world or try it for three trial passes. (The player can try a premium world as many times as he/she wants as long as he/she procures enough trial passes to do so.) There is also an option to buy Undersea World, Jurassic Jungle and Pharaoh's Tomb altogether for $2.99, which is usually a $5.97 value.
In both versions, there will be a delay of a few seconds if the player chooses to play in a different world, as the game can only hold one world in memory at a time and must take additional time to clear its memory and load the next world that the player has chosen.
The List of WorldsEdit
a. This is the main setting of all versions of Rail Rush.
b. These worlds are “seasonal” in that they correspond to three commonly celebrated Western holidays: Easter, Halloween and Christmas. These worlds are not available in the classic version, but are initially available in the other versions.
c. These worlds are special worlds that are playable in the Worlds and mobile version of Rail Rush. Only Steam Factory is initially available, while the other worlds listed in this category must be unlocked with twenty trial passes each (Worlds version), or in-app purchases (mobile version). Each of these worlds, with the exception of Zombie Caves, costs $1.99, while Zombie Caves costs $2.10.