Track laying

Owns a set of track pieces joined end to end, each with a type (straight, curve, slope, switch, bridge, tunnel, or special element such as a loop), an entry and exit position and heading, and a cost. Construction extends an open endpoint with a piece whose entry matches it; the game checks grade and curvature limits, terrain clearance, and collisions with other structures, then charges a cost that depends on terrain (slopes, water, demolition) and piece type. Railroad Tycoon and Transport Tycoon lay track on a tile grid, with slopes, bridges, and tunnels in Transport Tycoon; RollerCoaster Tycoon builds coasters piece by piece on a tile grid by direction, height, steepness, and elements such as loops and corkscrews; Planet Coaster adds spline editing; Factorio places straight and curved rail pieces. Outputs: a track graph that vehicles traverse, used by scheduling, signaling, and ride rating. Unlike free-placement, the unit of building is a connected chain rather than a footprint; unlike road-network, it owns segment geometry and its constraints rather than building connectivity; unlike modular-assembly, the result is a path.

Drawing a line through the world under constraints. Players hunt for the gentle grade around a hill, decide whether a bridge is worth its price, and fit a coaster's drops and turns into a cramped park. A clean line that vehicles run smoothly on is a craft object players admire and share.

• grade and curve radius limits and their effect on vehicle speed
• terrain cost model for slopes, water, tunnels, and demolition
• piece set: fixed tiles, free splines, or both
• auto-routing tools that pick a path between endpoints
• special pieces such as switches, loops, lifts, and brakes

• Tile-locked pieces make every layout look the same; free splines without snapping make clean joins hard.
• Construction controls that need many precise clicks per segment make building tedious.
• Costs too low make terrain irrelevant, so lines ignore the landscape.

• Terrain shapes networks and rides: lines follow valleys, and coasters use hills for drops.
• Junction and switch layouts couple track design to signaling and throughput.
• Track geometry feeds ride ratings and train speeds, so building quality shows up in revenue.

• Can route-finding assistants that propose track under grade and cost constraints keep the craft while removing click work?
• Could generative models propose coaster layouts that hit target ratings for players to refine?