Room Factory is a level editor meant for GameMaker games.
Currently very rough and incomplete, so I don't recommend using it for any important projects you may have.
The editor needs a game configuration file (*.rfcfg) for it to work at all. This file defines all of the objects, layers and some other general info for the game.
At the moment, the only configuration that is actively being worked on is the one for ANTONBLAST.
There is also a configuration for Pizza Tower and the Create Your Own Pizza mod, though right now it is only for testing and should not be used.
If you want to try and make your own configuration file, then you should look at the ANTONBLAST one, as that is the one that is most commonly updated and extensively makes use of almost 5679 every aspect the configuration format has.
Licenses are in the datafiles/licenses directory.