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If you ever played Locomotion, you know that this game has almost identical rail systems as Factorio.
Identical rail tracks to build on the grid, identical rail signaling system, very similar train routes planning etc.
There is only one big difference: Locomotion has S-shaped tracks!
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It allows building the very compact railway layouts like on this picture:
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In Factorio this simple crossing from track-to-track consumes a lot of space between rails. We really need the S-shaped rails!