Hi goliard!
Thank you for the kind words about the splash screen!
Regarding your issue: Yes, installing/running it directly inside the Itch.io App makes a difference.
The engine uses the native browser command prompt() to ask for the new scene's name. The Itch.io Desktop App's internal browser often blocks these popup windows for security/UI reasons, which is why nothing happens when you click the button.
The engine is designed to run in a real browser environment to function correctly as an editor.
Happy creating !