As some have reported, there are issues with the WebGL version of Unity. After several build attempts, I found settings that allow the game to work in WebGL via Firefox.

I suspect that the parameter that is problematic is this one :

These settings make everything work with the default Unity template.

Here are all my build settings in Unity

Feel free to give me your feedback to make sure it works on all other browsers

*You can also simply play my game on Firefox :smirk: *

https://ldjam.com/events/ludum-dare/52/pixel-artvester