Your system information

• Steam client version: 1777411435
• Distribution (e.g. Ubuntu): Ubuntu 24.04 & Ubuntu 25.10
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes
• GPU: Tested across multiple systems with different GPUs and drivers

Please describe your issue in as much detail as possible:

When running Steam under a bare Xorg session (no window manager), some games do not receive keyboard input events. Mouse pointer and click events works fine. Adding any window manager to the session fully resolves the issue.

This has been reproduced across multiple systems with different hardware and drivers.

Games tested - Mouse & keyboard works fine:

Games tested - keyboard input broken:

Notable observations:

• Both native Linux and Proton games are affected, so this is not
  Proton-specific.
• Mouse events are received normally in all cases, Under issue scenario
• Rise of the Tomb Raider works in windowed mode but breaks in fullscreen,
  suggesting the issue may be related to how fullscreen exclusive mode handles
  keyboard grab or focus in X11 without a WM present.
• Valve's own titles (CS2, HL, HL2) work correctly. Cities: Skylines is also
  Unity-based but works fine, which may help narrow down the root cause.
• The pattern suggests engines that rely on _NET_WM_STATE_FULLSCREEN hints or
  an explicit X11 keyboard grab may be most affected.

Steps for reproducing this issue:

1. Stop the GDM server ( sudo service gdm3 stop)
2. Start a bare Xorg session with no window manager (e.g. sudo /usr/lib/xorg/Xorg)
3. Launch Steam ( DISPLAY=:0 steam)
4. Launch the affected games such as Hollow Knight, Doom (2016) or Witcher 3.
5. Attempt any keyboard input in-game (movement, menu navigation, etc.)
6. Observe that no keyboard input is registered, while mouse input works normally.
7. Trying going to Windowed mode and relaunch the game, if games like Hollow Knight did receive the events.