Text was sometimes very small but somewhat readable.

While the controller worked fine the game has some hard-coded tutorial tool tips which do only show keyboard and mouse controls. Also the journal has hardcoded mouse glyphs for switching pages. You have to use "X" and "B" in order to read other pages.

Also in main menu the "Exit" button is not accessible via gamepad and the game has either to be force quit using the overlay or by using the touch screen.

Next certain buttons in the settings menu are not accessible like "Apply". But applying settings can also be done by just pressing "A" while hovering any option.

While this is not a Steam Deck but rather a game issue it is worth noting because the Steam Deck compatibility rating claims the game to actually show the right glyphs which it doesn’t.

While not noted in the Steam Deck compatibility notes the game has some areas where it get into the low 20s fps. Even after lowering any possible visual game option. Thankfully the game "most" of the time can maintain a somewhat 30ish fps mark so it is at least playable to some extend.

After playing the game in one go till chapter 6 "Edgar's Cabin" everything was fine. But upon starting chapter 6 the display kept all black. I could open the main menu and navigate it and even walk and jump according to sound effects. But nothing was visible. I had to quite the entire game and re-launch it in order to fix. I suspect this to be more like a game bug rather than a Steam Deck / Linux thing.