I understood what was going on pretty quickly--with two exceptions: I never did figure out what upgrading does, and I'm not sure what the Bone and Ectoplasm coins are for?
The main thing I wanted was the ability to auto-summon creatures at a given rate. As it is, I spend most of my time frantically clicking: It would have been nice if the creatures came out on their own (which they technically do, but only very infrequently).
Anyway! I thought it worked pretty well! It was fun to figure out how the towers worked... and then to construct a labyrinthine path to keep the creatures busy.
I took a few screenshots of things that I thought you might like to see:
The text here says "Spirit Lantern Unlock Unlocked."
In this photo, you can see the creatures climbing up without a ladder: You can reproduce this if you summon a huge amount of creatures at once and then move the ladder. (You can also get the creatures to pass through solid towers by placing items on top of them:)
This was also confusing to me:
The text says that there are 6 Furballs, but there are no Furballs anywhere to be seen. The battlefield is completely silent, and has been for a while!
My guess is that when the Furballs do eventually appear, there will be 6 of them. Is that how this works? If so, then this confusion could be eliminated if you added the word "Next: " along with a timer. Ideally, there would also be a tooltip that say you can increase the number of Furballs that autospawn by purchasing the "Upgrade" (assuming that's how it works, of course!)
The one thing that would improve the user interface the most is: Disable the "Necro Tower" button when you don't have enough money to build one (and make the button look different when it's disabled). As it is, you're seemingly able to buy and place the tower--only to have it turn red and disappear at the very end! I think this is the main reason why a lot of people were confused!