What resolution is your game? - I found it interesting where it seemed like you were restricting a left and right stretch - is this to not distort the pixel art?
First, thank you so much for playtesting and giving feedback on the demo! :D Your input was super helpful!
About 21:9, I actually haven't thought about it... But I will keep it in mind when I'm working on the resolution settings for the finished game, so maybe... What would be the benefits of 21:9 support in your opinion? Would it be just aesthetic, or gameplay-wise too?
I'm glad to hear my feedback was helpful, I could have been more thorough but I got caught up in enjoying the demo instead of making concise notes.
Having an ultrawide monitor it is just a matter of immersion, though I understand that there might be situations in which you want to use the standard 16:9 ratio to obscure things or just have one ratio to worry about, so if it isn't easy(ish) to implement don't worry about it.
Another tangent, but are maps going to be part of the game, I understand that they need to be made from scratch so I would understand if they weren't something being considered.