У вашего броузера проблема в совместимости с HTML5
Short demonstration of my main menu starter kit for UE 4.15. It has credits, settings (general, input, audio, display and graphics), a basic save system with screenshots saved within the .sav file and a level selection. It is designed to work well with gamepad and keyboard input. Button prompts switch from gamepad to keyboard icons right after you change your input device. Also works with mouse input of course.
The credits and level selection content as well as the general settings are customizeable in data tables without editing the widgets. Key rebinding is completely automated (currently only handles action mappings though).
Music: Heroic Minority by Alexandr Zhelanov
http://opengameart.org/content/heroic-minority