Totally Accurate Battle Simulator

This is less of a guide as to how to beat the campaign and more as to how to unlock it. Go into sandbox mode and find the map called Medieval 1 and once loaded in press F on PC (Not sure of the control on console) to free up your camera. Take your camera underneath and between the two islands and on your left you should see a glowing icon, look at it until it explodes and opens a door. Enter that door and then wait for a portal to open up. Once the portal opens up if you fly your camera into it it will take you to the fantasy good campaign levels.

Here is a video if you want to see someone do it instead