Source code included
For games that provide their source code along with the playable version, usually through some very restrictive license.
The first video game about Source code included was released on September 3, 1970.
Also, if source code is provided with no implicit mention of the source code in the license, then it falls under the license of the binaries (the runnable game and materials). If the game is proprietary, the source is proprietary as well.