A free & open-source 2D sprite editor, made with the Godot Engine
Java/JavaFX/Kotlin Game Library (Engine)
Arianne is an engine to develop multiplayer online games like Stendhal
GemRB is a portable open-source implementation of the Infinity Engine
Game engine to build text adventures.
An isometric arcade-style game of skill, puzzles and exploration
Action RPG that's easy to mod
Cross-breeding a 3D FPS with a fantasy RPG in the world of Hexen
General Purpose Engine for Graphic Adventures.
A free 3d game for PC that does not limit the player. Fight,Build,Gain
Heros of Jin Yong 3D Remastered
RTSish Game Engine
2D Game Engine
A RPG maker engine using Pygame
A fast, scalable, distributed game server engine/framework for C++
Opensource Game Studio
Real-time RPG for PC/tablet/phone; multiple quests and random dungeons