Super Alt S - Gaming Mode for KDE Plasma

Switch between KDE Plasma desktop and Steam Big Picture Gaming Mode with a keyboard shortcut. Built for Arch Linux and CachyOS.

Super+Alt+S to enter Gaming Mode. Super+Alt+R to return to desktop.

What's new (2026-05-16)

A round of CachyOS-compatibility and reliability work. No new shortcuts or user-visible flow changes, but several quiet footguns from the initial release are fixed.

• plasma-login-manager support. CachyOS now ships plasmalogin by default instead of SDDM. The installer detects which DM is active and parameterises every session-switch script, sudoers entry, and config path accordingly. SDDM hosts behave exactly as before.
• Proton-GE installed direct from GitHub instead of via the AUR's proton-ge-custom-bin, which had been silently failing. The new path is idempotent (skips if a GE-Proton* directory already exists) and SHA-verified.
• AUR resilience. Both the gamescope-session install and the optional-AUR-deps phase now check AUR reachability up front and retry the install up to 3× with 15s backoff. Stops the old "silent skip" mode where a transient AUR outage left the gaming session uninstalled.
• Fixed: CachyOS package conflicts. gamescope-session-cachyos (which Provides= the -git names but is missing files gamescope-session-plus needs) is now removed pre-emptively, then locked in IgnorePkg so pacman -Syu won't try to swap it back. Resolves the autologin black-screen loop a few users hit.
• Fixed: SDDM drop-in priority. Renamed /etc/sddm.conf.d/zz-gaming-session.conf → zzz-gaming-session.conf so it outranks CachyOS's own zz-steamos-autologin.conf (lexical sort). The old file is auto-removed during install.
• Fixed: Limine on CachyOS. When /etc/default/limine + limine-update are present, kernel-param edits go there (the source of truth) rather than to /boot/limine.conf, which gets regenerated on every mkinitcpio run.
• Post-install verification now hard-fails with a clear remediation message if gamescope-session-plus is missing after the AUR build, instead of letting you reboot into a broken session.
• Removed CFS sysctls from the sudoers entries (sched_migration_cost_ns, sched_min_granularity_ns, sched_latency_ns) — these knobs were deleted from the kernel when EEVDF replaced CFS in 6.6, so the sudoers lines just produced errors.

What it does

This installer sets up a full console-like gaming experience on your KDE Plasma desktop by configuring:

• Gamescope session using ChimeraOS packages (gamescope-session-git, gamescope-session-steam-git)
• Steam Big Picture running in a dedicated Wayland session via gamescope
• One-key switching between KDE Plasma and Gaming Mode — works with SDDM or plasma-login-manager (auto-detected)
• GPU auto-detection for NVIDIA, AMD dGPU, and AMD APU systems
• Performance mode with CPU governor, GPU power management, and kernel tuning
• NetworkManager integration so Steam has network access even if your desktop uses iwd/systemd-networkd
• External drive auto-mounting for Steam libraries on secondary drives
• Shader cache optimisation for reduced stuttering
• Installation verification to confirm everything is set up correctly

Requirements

• Arch Linux or CachyOS (or any Arch-based distro with KDE Plasma)
• KDE Plasma 6 (Wayland)
• SDDM or plasma-login-manager display manager (CachyOS ships plasmalogin by default — the installer auto-detects either)
• AMD or NVIDIA GPU (Intel-only is not supported)
• Steam (installed during setup if missing)
• AUR helper (yay or paru) for ChimeraOS session packages

Install

git clone https://git.no-signal.uk/nosignal/super-alt-s.git
cd super-alt-s
chmod +x super-alt-s.sh
./super-alt-s.sh

The installer is interactive and will walk you through each step, asking before making changes.

Usage

Action	Shortcut
Enter Gaming Mode	Super+Alt+S (from KDE Plasma)
Return to Desktop	Super+Alt+R (from Gaming Mode)
Return to Desktop (fallback)	Steam > Power > Exit to Desktop

Uninstall

Return to the desktop first (Super+Alt+R) — the uninstaller refuses to run from inside Gaming Mode, because it deletes the scripts the session needs to switch back.

From the cloned repo:

chmod +x uninstall.sh
./uninstall.sh

Run it as your normal user (not root) — it uses sudo where needed. Use --dry-run to see what would be removed without changing anything, and --yes to skip the confirmation prompt.

The uninstaller removes everything listed under What gets installed below — the switching scripts, the Gaming Mode Wayland session, the Super+Alt+S shortcut, the display manager autologin drop-in, and all sudoers/polkit/udev/performance config. It also offers (optional, default no) to remove the two AUR packages that exist only for Gaming Mode (gamescope-session-git, gamescope-session-steam-git), your autologin group membership, and the gaming-mode.conf config file.

Deliberately left in place, with how to revert each:

What	Why it's kept	To revert manually
Steam, gamescope, mangohud, gamemode, Vulkan drivers, python-evdev	Useful on their own; may predate this script	sudo pacman -Rns <package>
Proton-GE in ~/.local/share/Steam/compatibilitytools.d/	It's your Steam data	Delete the GE-Proton* folder
video, input, wheel group memberships	Commonly needed outside gaming	sudo gpasswd -d $USER <group>
nvidia-drm.modeset=1 kernel parameter (NVIDIA only)	Harmless (often beneficial) on the desktop; bootloader edits are risky to automate	Restore the timestamped backup the installer made (/etc/default/grub.backup.*, /etc/default/limine.backup.*, or /boot/loader/entries/*.backup.*), then regenerate your bootloader config
[multilib] pacman repo	Steam and other 32-bit software need it	Restore /etc/pacman.conf.backup.* or comment the [multilib] block out

After uninstalling, log out and back in (or reboot) to clear session environment variables and refresh the login screen's session list. If you use NetworkManager as your main network service, restart it (sudo systemctl restart NetworkManager) so it picks up its stock config again.

What gets installed

Packages (via pacman + AUR)

• Steam and all required 32-bit libraries
• GPU-specific Vulkan drivers (NVIDIA or AMD)
• gamescope, mangohud, gamemode
• Proton-GE — latest release pulled direct from GitHub into ~/.steam/steam/compatibilitytools.d/ (the AUR proton-ge-custom-bin is unreliable, so we skip it)
• gamescope-session-git + gamescope-session-steam-git (ChimeraOS AUR packages, with retry-on-failure + AUR reachability checks)
• python-evdev (for keybind monitoring)

Scripts

File	Purpose
/usr/local/bin/switch-to-gaming	Switches from KDE to Gaming Mode
/usr/local/bin/switch-to-desktop	Switches from Gaming Mode to KDE
/usr/local/bin/gamescope-session-nm-wrapper	Session wrapper with NetworkManager + performance mode
/usr/local/bin/gaming-keybind-monitor	Python daemon monitoring Super+Alt+R in Gaming Mode
/usr/local/bin/gaming-session-switch	Updates SDDM config for session switching
/usr/local/bin/gamescope-nm-start	Starts NetworkManager for gaming session
/usr/local/bin/gamescope-nm-stop	Stops NetworkManager and restores iwd
/usr/local/bin/steam-library-mount	Auto-mounts external drives with Steam libraries
/usr/lib/os-session-select	Handles Steam's "Exit to Desktop" menu option

System config

File	Purpose
/etc/sddm.conf.d/zzz-gaming-session.conf (or /etc/plasma-login-manager.conf.d/)	DM autologin session switching — zzz-* prefix outranks CachyOS's own zz-steamos-autologin.conf
/etc/sudoers.d/gaming-session-switch	Passwordless sudo for session switching
/etc/sudoers.d/gaming-mode-sysctl	Passwordless sudo for performance tuning
/etc/udev/rules.d/99-gaming-performance.rules	CPU/GPU sysfs permissions
/etc/security/limits.d/99-gaming-memlock.conf	Memory lock limits for esync
/etc/pipewire/pipewire.conf.d/10-gaming-latency.conf	Low-latency audio
/etc/environment.d/99-shader-cache.conf	Shader cache sizes
/etc/polkit-1/rules.d/50-gamescope-networkmanager.rules	NM access for wheel group
/etc/polkit-1/rules.d/50-udisks-gaming.rules	Drive mount access for wheel group

User config

File	Purpose
~/.config/environment.d/gamescope-session-plus.conf	Resolution, refresh rate, GPU settings
~/.config/kglobalshortcutsrc	Super+Alt+S shortcut registration

GPU support

NVIDIA

• Auto-detects NVIDIA GPU and installs required drivers/utils
• Checks and configures nvidia-drm.modeset=1 kernel parameter (supports GRUB, systemd-boot, and Limine)
• Sets up GBM backend and Vulkan adapter
• NVIDIA gamescope wrapper with --force-composition if supported
• Caps resolution at 2560x1440 for gamescope compatibility
• Performance mode includes persistence mode, max power limit, and runtime suspend disable

AMD (dGPU)

• Installs Vulkan RADEON drivers
• Enables adaptive sync and HDR
• Distinguishes between discrete GPUs and integrated APUs using PCI device identification

AMD APU

• Supported as a fallback when no discrete GPU is found
• Same session setup with APU-specific display detection

Verify installation

Run verification without reinstalling:

./super-alt-s.sh --verify

This checks all files, permissions, packages, user groups, and service status.

Options

./super-alt-s.sh              # Full install
./super-alt-s.sh --verify     # Verification only
./super-alt-s.sh --version    # Show version
./super-alt-s.sh --help       # Show help

How it works

1. KDE to Gaming Mode (Super+Alt+S): The switch-to-gaming script updates the display manager's session config to gamescope-session-steam-nm, kills any existing gamescope, and restarts the DM service. The DM auto-logs in to the gaming session. (SDDM and plasma-login-manager are both supported — the installer detects which one you're running and parameterises the scripts accordingly.)

2. Gaming session startup: The gamescope-session-nm-wrapper enables performance mode (CPU governor, GPU power), starts NetworkManager, launches the Steam library drive monitor, starts the keybind monitor, then hands off to ChimeraOS's gamescope-session-plus which launches gamescope with Steam.

3. Gaming Mode to KDE (Super+Alt+R): The gaming-keybind-monitor Python daemon detects the key combo via evdev and calls switch-to-desktop, which shuts down Steam, kills gamescope, updates the DM config back to KDE Plasma, and restarts the DM service.

4. Cleanup on exit: Performance mode is restored to balanced, NetworkManager is stopped (iwd restarted if needed), drive monitor and keybind monitor are killed.

Troubleshooting

No network in Gaming Mode

• Check NetworkManager is installed: pacman -S networkmanager
• Test manually: sudo systemctl start NetworkManager && nmcli general
• Check logs: journalctl -u NetworkManager -n 50

Shortcut not working in KDE

• Log out and back in after install
• Or set manually: System Settings > Shortcuts > search "Gaming Mode"

Super+Alt+R not working in Gaming Mode

• Ensure you're in the input group: groups | grep input
• Check python-evdev: python3 -c "import evdev"
• Check input devices: ls /dev/input/event*

NVIDIA: black screen or no display

• Verify kernel parameter: cat /proc/cmdline | grep nvidia-drm.modeset
• Reboot if you just added the parameter
• Check DRM cards: ls /sys/class/drm/card*/device/driver -la

Proton-GE not appearing in Steam

• Check it installed: ls ~/.steam/steam/compatibilitytools.d/
• Restart Steam fully (not just the window — quit from the tray) so it picks up new compat tools
• Re-run the installer to retry the GitHub download if the directory is empty

Black screen / login loop after entering Gaming Mode (CachyOS)

• Usually means gamescope-session-cachyos was reinstalled by a system update. Re-run ./super-alt-s.sh to remove it and lock it in IgnorePkg.
• Confirm the AUR build succeeded: ls /usr/share/gamescope-session-plus/gamescope-session-plus

License

MIT