I played the free demo of Factorio for about 10 hours and got hooked. Waited a bit to see if the price would go down, but it didn't and I didn't care. Bought it at full price and sunk a few hundred hours into it, which is some of the best entertainment ROI from a cost/hours perspective. It turned out to be a bad ROI from a general life perspective since I didn't do much else during that time, so be careful to not get too addicted.
Which is fine be me. First the game receives constant updates to this day. Second they're asking reasonable price to start with. Third the amount of content...