Caveman2 is an open source, high performance game engine written in C++ and released under the MIT License. It has been used to develop many successful commercial games including Kerbal Space Program, Prison Architect, and Verdun.
The game engine is known for its high performance, portability, and ease of use. It is also widely respected for its clean and well-designed codebase. These attributes make an attractive choice for developers who are looking for a powerful and easy-to-use game engine.