THIS IS OUT OF DATE. Follow the instructions on the TormStorm Github.

If you insist on using Lutris, the script published on the lutris website works so you may use that.

Unless you require RuneLite, I recommend you play using RS3 or OSRS from steam. Will integrate much more easily with the steam deck and doesn't require Desktop mode.

MAKE SURE YOU USE THE LATEST SCRIPT FROM THE TORMSTORM GITHUB.

Couple notes this this video is a little out of date:
The installer will no longer require force-quitting the launcher or even show the installer window
You may need to close lutris completely before Boilr will show the lutris entries.

Sorry about the bad quality. Open an issue on TormStorm github if you have any problems (sorry youtube won't let me post direct links).

prereqs (all from the steam deck software center)
Lutris
Boilr