I'm not really thinking of the time period the typical fortress / adventure starts or ends in, but after many ages of the world pass. Maybe the age of the dwarves comes, and with the forgotten beasts and mythical style creatures dead we end up with more complex machinery, digging machinery, composite materials, etc. You can spend more time on research when you're not dealing with insane fire breathing winged snails, I've been told.
Humans have the shortest life spans and might advance medicine due to that, tactics in war, weapons like everyone else, energy generation because the dwarves are no longer around to teach their now-mythical free-energy machines nor would they have anyway...
The elves might dominate and refine their love of trees into a potentially dangerous genetic engineering type scenario... grow trees harder than slade and nobody can cut them down easily, but the plant life itself starts becoming a threat to normally treeless biomes, water supply, etc in exchange for practically indestructible grown items.
Maybe one race doesn't end up dominating, but partners with another.
Clowns (if they're still around) might "civilize" and invent an
intentionally obfuscated legal system and
fast food. Or they might have sat around watching for long enough to realize that if the dwarves all need alcohol to get through the working day, they might eventually need far worse things to get through the day.
Maybe it isn't new technology at all... ever wonder where everything from the dwarven atom smasher ends up? Well, it's approaching critical mass in 3 other dimensions long forgotten about. The inhabitants are very angry about this lump of neutron-degenerate matter about a year away from collapsing into a singularity and are doing something about it... Welcome to the age of myth 2, electric boogaloo.
Those are just random examples. Half the technology invented might be useless in a given world, or developed in response to a problem that stopped existing by the time it was complete. Maybe it's still magic fueled, and magic is scientifically proven.
All complicated to program, but I feel like that's not as much an issue with this game as most