Why does my packaged game not launch in fullscreen unreal engine 5?

Question

Whenever I launch my game in standalone mode or packaged, the game doesn't go fullscreen even if I press F11 (shortcut to fullscreen / windowed mode).

Here's a demo of the problem : youtube link

If I put in the console r.SetRes 1920x1080, then the game goes fullscreen (for a 1080p screen). But end-users can't access console.

What do I do to make it go fullscreen?

Answer 1

The problem lies within window's screen settings (tested on windows 10 & 11).

One option in window is called "resolution scaling". When this is not 100%, then the game will not cover the screen (if scale > 100) or zoom too much in the game (if scale < 100).

In UE, there's an option to automatically ajust the game to window's scale setting. It's the "Allow High DPI in Game Mode" in the project settings (under Engine - User Interface). Check that to true and problem solved.