When I started playing the game, I played in DirectX because that's the default when you start the game through GOG Galaxy. I noticed some performance issues; framerates were inconsistent, and there was some noticable screen tearing when scrolling horizontally. OpenGL mode performs much better; no screen tearing, and framerates are noticably better/smoother. There are a few (very) minor problems, however:

1) The button icons. I play with a PS4 controller. When I played in DirectX mode, it showed the PS4 button icons. In OpenGL mode, it shows Xbox button icons. This has no effect on the gameplay, but it's still annoying. (NOTE: I use the DS4Windows app to play games with the PS4 controller.)

2) Cloud saves and achievements. I start the game in OpenGL mode by using the start menu shortcut. After playing in OpenGL mode, GOG Galaxy says that cloud saves aren't synced. Starting the game in DirectX mode and immediately quitting prompts Galaxy to sync the saves, but I shouldn't have to do this. There should be a "sync saves with the cloud" option in GOG Galaxy.

(It occurs to me that the problems I have are probably with Galaxy and not Dead Cells.)

3) Here's where it gets weird. I wanted to see if I could make Dead Cells start in OpenGL mode through Galaxy as the default. Steam has a "startup options" context menu that lets you do things like this. Galaxy doesn't. The closest thing I can find on the game page is More > Other > Dead Cells (OpenGL). Clicking on this launches the game in OpenGL... but in a graphically glitchy state. Attached are some screenshots of the title screen and start menu. I have no idea why it looks like that ONLY when I launch in OpenGL through Galaxy. I didn't go any further to see if it was playable.

Like I said, these are minor issues. I can play the game just fine. But I want to fix them anyway.

1) Not a proper solution, but you can disable icons: Settings > Misc > Hide controls in UI. Maybe this will be less annoying.

2) It could be related to Galaxy overlay: Settings > Features > uncheck Overlay right to In-game features. Your screenshots seems familiar, I attached one myself - when enabling Galaxy FPS counter, backgrounds in Dead Cells are vanishing for me.

The overlay in OpenGL seems to cause such problems. I play in OpenGL because the camera pans up constantly in DirectX mode and changing it to OpenGL fixes the problem for now. But without deactivating the overlay I have the same issue as 80-G.

Disabling the overlay did fix the graphical glitch. Thanks for that. As for the icons, I went ahead and changed that setting. It's not exactly what I wanted, but I can live with it.

Sorry for necro this, but I couldn't find a newer topic to this and this old problem seems to be resolved.

I just noticed this in the changelog of Galaxy: Dead Cells is not listed but since I running it in OpenGL, because of the problems mentioned above, I checked if this solved the overlay problem and it did. Now I can use the screenshot function and the overlay. Thank you GOG. :)