I had 39 crystals but I still couldn't make another miner. The instructions weren't very precise. I liked the soundtrack and the animations though, I didn't get to mix monster cores but shadows were fully present :D
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Yes. It can be a little confusing. The total crystal count at the top is the combination of all bases. Even if you had 39 crystals total, one base may only have 20, while the other has 19, so neither could spawn a new miner.
If I was was able to create a more in-depth tutorial and more easily readable GUI, I would try to achieve better communication of these nuances.