I can say that indeed layers of slate vary in thickness and appearance. Trust me. I'm not a geologist but I always wanted to be one. (Kinda like Trader Jen - she's not displayed her shingle (diploma) - hold up there @SnowDog1942). At one time not too long ago, slate shingles were common on roofs. These were replaced by more modern (lighter weight) materials and since these slate tiles were hand-hewn and had perceived value, they were stored. To come back as machined-out coasters for this game. Wouldn't mind having one but probably kinda late for that.Perhaps individual slabs of natural slate just vary a lot in thickness and luster? We need a geologist... @DaVegaNL?
A better, non toxic response would just be to say that you don't like it and then move on.
But hey, if you can do better, nobody is stopping you from starting up your own PC gaming software company, developing and putting out an unique game, and then creating merchandise for that game.