There are 5 repositories under rts-engine topic.
An OpenGL RTS game engine written in C
A cross-platform open-source reimplementation of the Age of Empires (1997) engine
An RTS engine written in golang. Detaches the engine from the UI via a TCP/IP API. Any UI could be hung off of this. Tailored for large numbers of simultaneous players within a large world.
Simple, lightweight game engine for RTS games
A game engine written in C++ made to make making developing RTS games easier.