My goals was just that, for it to be played by people wanting to play the original campaign again, but not have it feel like a tutorial. I wanted to stay close to the original campaign though.
Most transfers I hid behind secret objectives, mostly because most maps if you start with a transferred creature you can just cheese the level straight away to win.
I don't think the original campaign lends itself all that well to a defensive play style. Mostly, because you're never really attacked and you can't win by sitting in your dungeon. You have to go attack to actually win. And the maps where you can just sit and wait forever until all your creatures are level 10, you could have easily won when your creatures were level 6 as well. But which maps do you think are too obviously exploitable by a lava trap or something?
Level
10 I think is actually pretty ok now, I think blue attacks pretty soon and you'd better be ready for it.
The campaign is a few years old now, perhaps I'll revisit it sometimes to see where I can tweak it. I was considering changing up some of the still untouched secret levels, and perhaps make it so you can complete them only once for a permanent bonus.