I made the map for my application using the Unreal Engine.
I had no previous experience with coding or level building (well, a little bit of tinkering with TI-86 graphics calculators and some messing around with Duke Nukem's Build
), and so working with the Unreal Engine was a pretty monumental challenge.
I highly recommend taking this challenge on though, there's an excellent tutorial resource you can find here:
http://architectonic.planetunreal.gamespy.com/first_level.html
It took me a very long time to go through those tutorials, but I couldn't have produced anything without them. As an added bonus, the Unreal Editor is a fair bit more complicated to use than Heroblade, and so if you really do go through all these tutorials and make a great map, if you're accepted you'll find it easy and fun to learn how to use heroblade.