Google maps for block game
Open source simulation game based on Transport Tycoon Deluxe
KotCity, an open source city simulator
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
A comprehensive path-finding library for grid based games
C++ OpenSource Game Fabric based on SDL2
Fast and easy-to-use pathfinding library for grid-based games
A game engine in java for 2D strategy games
Cross-platform 2D game engine
SmartMap is an easy desktop random world creator.