`rayman2` can be created by using the command line option `--extract-data "folder"`. The `folder` variable should point to a valid Rayman 2: The Great Escape installation.
`rayman2` will be copied into the OpenRayman data folder (in `data/games`). This is all that needs to be done to run OpenRayman.
Do note that OpenRayman contains some extensions to the Rayman 2: The Great Escape game, such as more menu options.
If you for some reason wish to run without these modifications then you will either need to edit the `config.json` file and change the `game` variable from `rayman2_openrayman` to `rayman2`, or by specifying the game to run via the command line option `--game rayman2`.
You should always target `rayman2_openrayman` when making a mod.