Hi! I'm glad you liked it. I'm not sure what could have cause the bug. I'll see if I can look into it. But you can probably fix it by just reloading the page (the game auto saves)
I saw this same thing right as I was heading into a boss fight. Reloading fixed it. Later I saw a similar problem after a boss fight. I ran out of the boss area and there was just an empty blue background beyond that. The character fell off the bottom of the screen.
