You only have one life. Once you die your character wont respawn. Similar to Minecraft hardcore.
Small changes concerning balance, gameplay, or graphics.
New ways to deal with enemies, be it attack or defense.
Changes to enemies or entirely new enemies to deal with.
So after you die can you go into "Brave New World" mode?
Is that an option that shows on the Respawn screen? Can you share what you are seeing and what mods you have installed?
I was just guessing based on "once you die you don't get another body."
Because Factorio is almost completely playable without a body once you have construction bots up and running, and v2.0 will plug the last few spots.