Apart from 'Jagex Launcher' (not being obligated) players are able to download 2 'StandAlone Clients', RuneScape and OldSchool. You are able to find these clients ... in '
Currently, the Launcher is optional. Eventually, the RuneScape and Old School RuneScape standalone clients will no longer be supported. If you don't want to use the Launcher just yet, you can follow these links to install the standalone
RuneScape
or
Old School
clients.
The 2 links in these text are the links to 2 'StandAlone Clients'.
These clients allow you to play both versions without the need of 'Jagex Launcher'. If players 'first' make these clients working (download/install/play) they are for sure able to play both versions separately without Jagex Launcher.
Once that is accomplished you can now download/start 'Jagex Launcher' where 'Jagex Launcher' is able to find those 2 standalone clients on your computer and use them for future play of RuneScape, through these clients.