Full (AI) disclosure: in June this year (2026) I bought a full AMD stack gaming PC and installed CachyOS. I've read all documentation on CachyOS Wiki and was tinkering with games and was using Mistral to analyze problems and find solutions.
This is the report Mistral generated from my experiences. As with anything AI I've checked everything and edited some fluff out and added some important bits.
By the way Mistral told me to report this here so the dev/community can benefit from our findings. First time in my life I do something because AI told me to (I also agree with it otherwise I wouldn't do it).
System:
After setting in-game fullscreen once, every subsequent launch plays audio and the process runs, but nothing is rendered — no window, no display mode change, game otherwise alive. Only fix found: editing ~/Documents/My Games/Gruntz/settings.toml and setting displayMode = "Borderless" (or windowed.
Issue 2 — Windowed mode opens at the wrong size
With the desktop at 3840×2160 @ 225% scaling, windowed mode opens at 1707×902. That is exactly the logical desktop size (3840/2.25 = 1707 × 2160/2.25 = 960) minus the titlebar, so the game appears to size its window in logical pixels and render at that resolution, which the compositor then upscales. Looks small and soft at 225%. Setting displayMode = "Borderless" mostly works, but the game still starts oversized and the correct state has to be forced via right-click on the taskbar entry → Fullscreen on every launch — the setting doesn't fully apply at startup.
Issue 3 — Cursor offset under gamescope
To work around the above, I run the game through gamescope (gamescope -W 3840 -H 2160 -w 1920 -h 1080 -f --force-grab-cursor -- Gruntz). Rendering at 1920×1080 fixes the in-game UI scaling nicely, but the cursor is offset from its actual position making the game unplayable. The offset persists with:
Summary / asks:
GAME="/home/<username>/Games/Ahwoo/Gruntz/Gruntz"
# -w 1707 -h 960 \
# -w 1920 -h 1080 \
exec gamescope \
-W 3840 -H 2160 \
-w 1920 -h 1080 \
-f \
-- game-performance "$GAME" "$@"
This is the report Mistral generated from my experiences. As with anything AI I've checked everything and edited some fluff out and added some important bits.
By the way Mistral told me to report this here so the dev/community can benefit from our findings. First time in my life I do something because AI told me to (I also agree with it otherwise I wouldn't do it).
System:
- OS: CachyOS (up-to-date as of Nov 2026)
- Session: KDE Plasma, Wayland
- Display: 4K Samsung TV (3840×2160, 8 years old), desktop scaling 225%
- CPU: AMD Ryzen 7 9800X3D (16) @ 5.27 GHz
- GPU: AMD Radeon RX 9070 XT
After setting in-game fullscreen once, every subsequent launch plays audio and the process runs, but nothing is rendered — no window, no display mode change, game otherwise alive. Only fix found: editing ~/Documents/My Games/Gruntz/settings.toml and setting displayMode = "Borderless" (or windowed.
Issue 2 — Windowed mode opens at the wrong size
With the desktop at 3840×2160 @ 225% scaling, windowed mode opens at 1707×902. That is exactly the logical desktop size (3840/2.25 = 1707 × 2160/2.25 = 960) minus the titlebar, so the game appears to size its window in logical pixels and render at that resolution, which the compositor then upscales. Looks small and soft at 225%. Setting displayMode = "Borderless" mostly works, but the game still starts oversized and the correct state has to be forced via right-click on the taskbar entry → Fullscreen on every launch — the setting doesn't fully apply at startup.
Issue 3 — Cursor offset under gamescope
To work around the above, I run the game through gamescope (gamescope -W 3840 -H 2160 -w 1920 -h 1080 -f --force-grab-cursor -- Gruntz). Rendering at 1920×1080 fixes the in-game UI scaling nicely, but the cursor is offset from its actual position making the game unplayable. The offset persists with:
- --force-grab-cursor
- render size = output size (1:1, no scaling)
Summary / asks:
- Fullscreen mode appears broken under KDE Wayland fractional scaling (invisible game). Borderless via settings.toml is the only working mode, and even then it needs a manual taskbar fullscreen nudge each launch.
- Window sizing seems to use logical pixels and doesn't apply the saved display mode correctly at startup.
- Any in-game UI scale option (or a fix for windowed rendering at high-DPI) would remove the need for gamescope entirely.
GAME="/home/<username>/Games/Ahwoo/Gruntz/Gruntz"
# -w 1707 -h 960 \
# -w 1920 -h 1080 \
exec gamescope \
-W 3840 -H 2160 \
-w 1920 -h 1080 \
-f \
-- game-performance "$GAME" "$@"
