TripleA - TripleA is a free (under GPL) turn based strategy game based on Axis & Allies board game.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Lux Delux - Lux Delux is a game of strategy and domination inspired by the board game Risk.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
Streets of Chaos - Streets of Chaos is a Puzzle, Tactical, Turn-based Strategy and Single-player Simulation created by SimProse Studios.
BYOND - BYOND is the premier community for making and playing online multiplayer games.