EDIT: I'm downloaded and I like it! Sandbox mode is possible? (Without Fire)
unfortunately this is the only game mode. Everything is balanced to make it possible to complete the level with a good amount of understanding, but it's impossible to go infinite since the components take damage over time and sooner or later somthing will break. The purpose is to survive the day!
Fire is annoying, I know, it's there to be so! I might consider nerfing it a little bit if it is a big problem.