I have hundreds of hours of playtime in the non-steam version. I can safely say that Dwarf Fortress is one of the best and biggest games of all time. It is a game in which losing is Fun (and also expected.)

You and your colony of dwarves will experience hardship, hunger, the elements and probably more than just one night creature, were creature or goblin attack. Some may die, others may come from afar to join your bustling outpost. The detail is so significant that individual bones/body part segments (finger parts) may be severed in combat or during Unexpected Expeditions.

Who am I kidding? Most forts will be annihilated by tantrum spirals, the green tide, an invading army of skeletons and zombies or just really REALLY annoyed elves (because of all the deforestation, naturally.) So everyone will die, and you'll strike the earth again. New outpost, new dwarves.

Did I mention that an entire world is created for this, including tens of thousands of historical figures (and all their interactions, legendary objects they've created, gods they annoyed and got cursed by, settlement expansions, child-being-abducted-by-goblins and ending up as ruler of a goblin pit somehow)

It's just. It's a thing. Buy it.