Start each level with several train cars of different colors and types on separate rails. Your goal is to strategically move and align four identical train cars onto one rail. Connecting two or more identical train cars allows you to select them all for easier manipulation. Once four train cars of the same type are on one rail, a train head arrives to pull them away, completing the sorting process.
As you progress, the map expands, introducing more rails and train cars, increasing the challenge levels.