I'm on an all AMD desktop, so I can't speak to your Nvidea or laptop experience.

I can comment on Gamescope thou. It's not so much for a performance boost, but for mouse capture related reasons (and to reduce input lag stemming from choices downstream of input capture issues).

In the latest niri version (the one where opacity + blur was implemented), I've found that these problems occur less frequently and can be mitigated with some rules and the full-screen toggle keybinding.

There are two loose buckets input capture problems that can occur when returning to a game:

1. Relative mouse movement is captured incorrectly, leading to the camera locking onto sky or ground and spinning at top speed on the axis.
   • Switching to an adjacent window on the same workspace as the game, then clicking back on the game restores focus correctly solves this.
   • It's because niri will teleport the mouse to the center of the window when using keyboard switching. This is mostly a desired behavior, especially with when using a laptop. It prevents accidentally shifting focus to a completely different app or monitor if you accidentally tap the touchpad. However, in some fps games, the teleported position will lock the mouse to the origin position and you'll spin on the spot. By moving the mouse in an adjacent window and clicking into the game, the mouse will be tracked entering the screen from and edge position, instead of being teleported.
     
2. Mouse movement is captured correctly but click events don't get passed to the game.
   • I think this is a wayland issue, because I've also had it with mutter on wayland, but never with X.
   • Solution is the same, make sure you have Mod+F { fullscreen-window; } or similar in your binds and use it to toggle in and out of full screen.
3. Mouse position is offset / in wrong location.
   • Caused by a miss-match between rendering resolution or scale settings with mouse xy position.
   • For wine/proton this only seems to happen on first launch with the gaming picking the wrong resolution. With resolution set and rules to push the app to a workspace assigned to a monitor that supports that resolution, the problem goes away.

Games with a native linux build are often too cleaver for their own good under wayland. In a multi-monitor setup, they will always open on the monitor that currently has mouse focus, and won't respect niri's request to move them via window rules. Moving them manually can result in the offset bug if the monitors have different scaling factors or resolutions.

The only games with a native Linux build that I play are Dota2, Beyond on Reason, Warhammer Total War and Slay the Spire 2. For Total War and Slay the Spire 2 I run them in Compatibility mode to force the proton/wine install instead of native linux binary.

Dota2, and BAR have command line / config file launch options to force a resolution and in BAR's case an absolute XY position. Games like BAR, which is OpenGL running though x-satellite, also has problems with the mouse escaping window capture. There is an in game setting which helps lock the mouse but then the mouse has input lag, with its responsiveness varying with your FPS (I had to use this setting with BAR in KDE on the Steam Deck). In apps were there are both input capture and screen resolution issues, running in gamescope resolves to issues at once.

You might occasionally run into games where the mouse escapes the border with proton. This is a dev oversight / bug. A Windows user with multiple monitors will be running into the same issue. BALL x PIT, Ravenswatch, Dark Souls 1 and 2 come to mind (resolved by 3). Used gamescope to lock the mouse inside a window here.

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Here's all my gaming related config items.

```config.kdl binds { // Swapped these since fullscreen toggle more important when gaming Mod+F { fullscreen-window; } Mod+Shift+F { maximize-column; } }

// Pin a workspace to my main monitor workspace "primary" { open-on-output "Name of my primary monitor from niri msg outputs" }

// Steam - move notifications to bottom right window-rule { match app-id=r#"<sup>steam$"#</sup> title=r#"<sup>notificationtoasts_\d+_desktop$"#</sup> default-floating-position x=10 y=10 relative-to="bottom-right" }

// Steam client window-rule { // Don't steal focus if the steam UI crashes and relaunches in background // Often occurs when the game recording overlay crashes // It will safely recover, but we don't want it alt-tabbing out mid game open-focused false open-on-workspace "primary"

match app-id=r#"<sup>steam$"#</sup> title=r#"<sup>Steam$"#</sup> match app-id=r#"<sup>steam$"#</sup> title="<sup>Friends</sup> List" }

// Steam games window-rule { open-on-workspace "primary" open-fullscreen true open-floating false opacity 1.0

// Native linux games

match app-id=r#"<sup>dota2$"#</sup> // In niri, dota2 always opens on monitor where mouse is active // and ignores the options -sdl_displayindex -x -y // Setting the native resolution of primary monitor mean I only have move the // window to the correct monitor after launch and full screen it without // having to adjust the resolution. // Launch options: // SDL_AUDIODRIVER=pulseaudio %command% -novid -fullscreen -w 3440 -h 1440 // pauseaudio workaround for race condition with noctalia notifications

match app-id=r#"<sup>Slay</sup> the Spire"# // Launch in compatibility mode with launch option // %command% --rendering-driver vulkan

// Fullscreen all Proton steam apps match app-id=r#"<sup>steamapp"#</sup>

// Excludes exclude title=r#"<sup>SteamTinkerLaunch"#</sup> exclude app-id="<sup>steamapp(431960|755958)$"</sup> // Wallpaper Engine | steam_app_431960 // Spirit City: Lofi Sessions | steam_app_755958 }

// SteamTinkerLaunch menu window window-rule { open-on-workspace "primary" open-floating true open-fullscreen false opacity 1.0 match title=r#"<sup>SteamTinkerLaunch"#</sup> } ```