Ah that's a shame, none of us have ultrawide monitors so we wouldn't have been able to test that.
Unfortunately, I don't think we'll be able to get a WebGL build as we are using Compute Shaders for the goo mechanic, and WebGL does not support them (which is something we just decided to accept and to focus on making a playable, downloadable version).
Thanks for the comment!
After the jam, if you decided to update the game, you can go into the project settings and enabled "resize window". This will allow users to force the game into a window from full screen and then resize it to fit their monitor. This can cause weird issues with the UI however if it isn't designed to scale well (which typically is a bit of a problem with Unity I feel). Just a little tip I figured out while play testing my games in the past. I love my ultrawide for work, but it definitely causes issues with gaming at times (i run most of my games in a window lol).
