
Controller support is horrendous when interacting with the interface. Make sure to set cursor controls, especially to click and drag comfortably.
Lower graphics settings, lock the FPS to 30. The Deck can't maintain a consistent 60 FPS in this game, so either lock it to the highest it goes or 30.
The first time the game loads every time you open it is rather slow.
This game is a major pain on the Steam Deck. Installing it takes much longer than any other game, actually starting to play it takes ages every time you launch it, updating it is also much slower than any other game, and even uninstalling it is a pain. I kid you not, this thing messed up the wifi adapter when I uninstalled it. I couldn't download anything, cloud saves wouldn't sync, and even my playtime didn't register on another game after I uninstalled Gedonia. I could still access the store, but it's as if it turned off wifi or something (even though it was on and I had signal). I don't know why this game is such a pain on the Deck, but the dev knows it's a problem and it seems like he's not that interested in addressing any issues. Other than that, I didn't find the text particularly difficult to read. There's a UI scaling setting, but use it with caution as it will make some windows impossible to use (e.g. the crafting window). Ignoring all that, it plays alright, but this game is just not worth the hassle. There are better RPGs that run flawlessly on the Deck. If you're reading this and considering playing it on the Deck, don't. You probably have a Windows machine somewhere, be it a PC or a gaming laptop, so play it there instead.
If mouse doesn't work that is game bug. Presing Tab, Esc or the menu keys shoud fix it
If Mouse doesn't respond it is becuase the game thinks your are in a menu or tab focusing on something. Press Tab os Esc to fix
First time it worked perfectly. After that mouse cound't move the camera but it still worked in menus. Changing to Proton 9 (Beta) Fixed it
VK_ASYNC=1 PROTON_NO_ESYNC=1 gamemoderun mangohud LD_PRELOAD="$LD_PRELOAD:/usr/\$LIB/libgamemode.so" %command%
It crashes when loading the world.
PROTON_USE_WINED3D=1 %command%
It crashes when loading the world. Main menu - OK, char creation - OK, loading screen - crash. Past week it works fine without any additional prefixes. Broken now. Only works with PROTON_USE_WINED3D=1 %command%

Just worked for me on proton experimental. The loading screen did take a while, but then I got in.
Once you get loaded into the game world, you won't see anything past the loading screen. You can hear that the game is running, but the loading screen never disappears. This also happens on my desktop running Arch.

Rarely the game freezes to load assets

Runs quite well.
A few slowdowns, but nothing game-breaking.
Game now runs out of the box. Not certain why - either because game was updated a couple of days ago, or something in the system was updated.

Game doesn't start
Should run (as it appears to use Unity) but game never starts. Executable runs using 100% CPU, but not even a black screen.
Game runs through Unity and of the box in its current form. It is currently in Development, but has no noticeable issues in running.

Works as well OOB as you would expect from early access title.
Probably performance problems due to Early Access status.