Hey MrSandyClaws,
You need to create a shortcut (Instructions on how to do this are above, but I'll put them in this post too)
Find the shortcut for the RuneScape client, and copy and paste it. Right click the new copy and go to 'properties' - 'shortcut' - and change the end from
\bin\JagexLauncher.exe runescape
to...
\bin\JagexLauncher.exe gameyouwant - eg \bin\JagexLauncher.exe dungeonassault
When you've done this, apply the changes, hit OK, and then run it using the shortcut you created. You can now rename it too.
You've got a funorb game client that isn't reliant on Java, nor browser support! Yaaaay!
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In your specific case, you need to change
\bin\JagexLauncher.exe runescape
to
\bin\JagexLauncher.exe arcanists

Save/apply, make sure the prm is saved, and then run the shortcut, and you'll have your own funorb client.