Each departing and arrival station has a color, trains leaving from a red departing station will always be red. The user has to use traintracks to connect the departing and arrival stations to each other, getting the differently colored trains intro their stations.
Trains can intersect and be merged with each other. A yellow and blue train will merge into a green train. Two red trains intersecting will stay red, but a red and a yellow train crossing each other will result in two orange trains.
The colorblind will have trouble with recognizing these colors and linking colors of stations and trains to each other. The blue/purple, green/yellow, red/green and red/orange combinations can prove difficult.
Thankfully, the game has an amazing colorblind option. Enabling this option adds the first letter of the color to the trains and stations, B for blue, G for green, etc. The colors itself do not change, only the letters are added.
This helps the colorblind in two ways:
- Instead of matching colors it’s now possible to match letters to each other
- The letters help naming the colors, making the color combinations easier
The game requires you to think on many levels; spacing, combining trains, timing, the number of trains and combining colors.
You can play using different tactics, I’m very visually oriented while a friend of mine used a more mathematical approach using various loops. This shows how complex some puzzles can be.
While the color palette is not radically difficult (very basic colors, no shades, good contrast), it does add to the complexity. Actively having to think about the color of a train adds another layer of complexity, it’s not part of the game and thinking about it distracts you from the actual puzzle.
As a separate option, it does not get in the way of normal users. Non-colorblind users have no need for the letters as the color of the train is all you need.
This differs from how the icons in wordfeud work, where color is not enough to convey information on it’s own.
Having the colorblind option then is very useful. It levels the complexity to be the same for colorblind as it is for non-colorblind users.