as progression fantasy goes, this was interesting. Tower Defense is something I've not seen handled before, so if you accept the idea that the GM basically sets you up with scaling resources from the beginning you're good to go. This is a bit like suspending disbeleif in typical fantasy books I suppose: this doesn't have to happen in your general progression because the MC goes and does stuff around the world, rather than the world being forced into his small area of it.

That aside, I enjoyed the writing. My second Australian one, too.