Hey Bg !
Yeah, some PC will have a hard time running that game, it's because of the PIXI shaders and masks used to make the "revealing effect", as well as the water and fog effects. It's some code runned by GPU only, so some chipsets or old graphics cards will not be able to process that. It's something still very new to me and I will definetely try to optimize that in the future. :)
I'm really glad you managed to play it. Undo a building is a pretty good idea and I was actually trying to do it when I ran out of time, sadly. But anyway, I'm happy you played it and you enjoyed it, even tho you have hit some limitations of this game/prototype.
See you around and stay safe, Bg ! :D