Citadel is a faithful remake of the original game System Shock created in 1994 by Looking Glass Studios.Genre: Puzzle, Shooter, Adventure, Action
XLE is a open-source (MIT license) game engine currently in development at XL Games.
The good old days of Minecraft, brought back in all their simplistic glory.Genre: Construction and management, Adventure
OpenGOO is a free and opensource clone of World of Goo game, written in Qt 5 and Box2D as a 2D physics engine.Genre: Puzzle, Action
This is a game about a brave warrior - a teenage boy who alone was forced to fight an evil troll and his companions.Genre: Beat 'Em Up, Action
The Cafu Engine is an all-purpose, modern 3D graphics engine and game development kit, feature complete to get you started quickly.
Free open-source game engine for FreePascal and Lazarus.
Raydium is a game engine. It provides a set of functions wich allow quick and flexible games creation.
The SGE Game Engine ("SGE", pronounced like "Sage") is a general-purpose 2-D game engine.