У вашего броузера проблема в совместимости с HTML5
This game is still currently in development from what I can tell, I may or may not finish the demo. Here's the link to the game developer's blog and Patreon, which is Uru, it'd be great if you all supported this work.
https://www.patreon.com/uru0000?ty=c
http://ururu0000.blog.fc2.com/
Anyway, this RPG game begins fighting the "Demon King", or the final boss of the game, or so you think. After defeating said demon king, another one appears with the same form as the one before.