Battle for Wesnoth: open-source, turn-based strategy game (wesnoth.org)

The Battle for Wesnoth is a free, open-source, high-fantasy turn-based strategy game offering single-player campaigns and online or local multiplayer battles. The site highlights hundreds of units across multiple factions, extensive modding support using WML and Lua, and a library of player-made add-ons available via an official server. It also distinguishes between a stable release for general play and a development version aimed at experienced players and content creators.