SteamGamepadUI=1 is also set when Steam launches from Big Picture on an
ordinary desktop, which is broader than Steam Deck / gamescope. Detection is
now XDG_CURRENT_DESKTOP=gamescope, GAMESCOPE_WAYLAND_DISPLAY or SteamDeck=1
(plus --game-mode / PSX_GAME_MODE); game_mode_test and docs updated.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Detected from a gamescope session (XDG_CURRENT_DESKTOP, GAMESCOPE_WAYLAND_DISPLAY)
or Steam's gamepad UI (SteamGamepadUI=1); --game-mode / --no-game-mode and
PSX_GAME_MODE override. When on and a disc is set up, the launcher is
skipped and the game opens borderless fullscreen for that run (the saved
Fullscreen choice is untouched); the first run still shows the launcher so
the disc can be picked. Desktop sessions, --headless and --hidden-window are
unchanged. game_mode_test covers detection and precedence; docs/GAME_MODE.md.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Matthew Stanley