Thanks for your thoughtful feedback @vicvondoom! I did look at HIVE games such as Terracore, Golem Overlord, and Splinterlands, to see what I wanted to emulate, as well as what didn't work, but this is my first game, so I'm sure there are things I haven't thought of.
DemoniCore has only one token, DCORE, for simplicity - As much as I enjoy Splinterlands, I don't like how they have multiple tokens that all compete for utility and value against each other. Another reason that DemoniCore only has 1 token, is that creating new tokens in Tribaldex isn't cheap (particularly if you want to enable staking), and I am operating on a shoestring budget :P
If it is a mistake to only use one token for a game, I'd love to understand the reasons why. When I have a little more pocket money, I would be open to creating another token, if it would result in a healthier game economy. GO and Terracore have fewer tokens than Splinterlands, but still more than one, which I'm sure is for good reason.