A plain packaged launch (./GigLine.sh with no -map) opened
/Engine/Maps/Templates/OpenWorld — an empty engine template with nothing to
do, which presented as a 'stuck' window with no working mouse/keys. The
GameDefaultMap setting lived in DefaultGame.ini and wasn't taking effect.
Move GameMapsSettings (GameDefaultMap/EditorStartupMap/ServerDefaultMap/
TransitionMap = /Game/Hollywood/DemoMap) into DefaultEngine.ini alongside the
GlobalDefaultGameMode, and drop the stale ReviewMap default from DefaultGame.ini.
Verified: plain ./GigLine.sh now loads /Game/Hollywood/DemoMap, Enhanced Input
initializes, Vulkan window opens.