So last night I was half sleeping and mining stone to get my tower higher, and I made a huge dent in my basement quarry, and I added 20 levels to my tower.
Today I went into my basement to start the furnaces burning again, and all the rock I mined was replaced.
Then I went up to the top of my tower, and saw that something really odd had happened:
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I have seen where progress had been wiped due to a server setback, but this is really really odd. How is it that only random parts were reset? The tower should be solid, now I have some really nice windows....