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

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