OpenRCT2 - Game engine recreation of RollerCoaster Tycoon 2 adding new features.
OpenTTD - An open-source clone of the classic game ...
Parkitect - Build the theme park of your dreams, and keep it running!
Simutrans - Simutrans is an open-source transport simulator.
Planet Coaster - Planet Coaster is an Adventure-based, Management, Strategy, Sandbox, Building, Single and Multiplayer Simulation by Frontier Developments.
Transport Tycoon Deluxe - Transport Tycoon Deluxe is a Business Simulation developed by Chris Sawyer and published by MicroProse.