So I was tired of all the futuretech the dwarves were developing (This is a FANTASY game after all), so I set the world gen for just a couple hundred years. Just enough for a bit of society to form, develop some nice civilizations and all that. Booted up dwarf mode, and built a really sweet tower out of a tall mountain. I even set up some sweet ballistas, thanks to one of my mechanics getting a strange mood and designed a freaking powerful ballista design, on the top of the tower and on some of the outcroppings. Which was handy since kobolds became super badass in this world, conquering dwarven and goblin civilizations and combining their tech (mostly dwarven gearworking with some goblin leatherworking and weaponry) and made large zeppelins. They weren't much of a threat to my awesome fort but they kept attacking by air.
Then the Kobolds made peace with me. They just sent an ambassador at me out of nowhere and the ambassador asked for a small sum of cash and permission to build near us in exchange for protection and goods. It was pretty nice. I accepted despite the fishiness of the deal because I wanted my own zeppelins. I spent a good summer building a large hangar for my zeppelins and I was sending dwarven traders around the world with my goods. Brought in lots of wealth let me tell you. I didn't trust the kobolds and still kept a very active military but they proved to be good trade partners. A while later, a kobold ambassador came and requested 5 dwarven marksmen and designs for our ballista. I was like pffft no, but then I read what they were offering. Fucking railguns. I kid you not. So obviously I accepted, low-tech desires or not.
Laterwards something odd happened. A spaceship just crash landed near my fortress, off the main map. I sent over a dwarven zeppelin to watch, and after watching a couple procedurally generated aliens with railguns mill around a bit, a Kobold zeppelin (armed with what I guess was a combination of the railgun tech and my ballista design no less) flew in, landed, and delivered a squadron of kobolds (and some dwarves, humans, and elves) all armed to the teeth with various high tech armaments. They were called the Knights of Killing. Anyways they lived up to their name, killed the aliens and flew off, with a second zeppelin arriving later to reclaim the aliens stuff. I laughed at the Kobold XCom project but realized this ruins any hopes of having a low-tech game. I guess that's what they were "protecting" me from? Anyways, a kobold ambassador showed up and demanded not to spread word of what I saw, and in exchange they gave me railballista tech so I reoutfitted my tower. Sadly, I never got a chance to use my awesome defense against UFOs flying nearby.
A few summers later and it turns out that I was the kobolds remaining ally. All the other civilizations had either been conquered or abandoned their peace treaty, no longer funding the Kobold's very XCom-esque project. Not long afterwards, a couple alien battleships showed up, completely overrun my defenses, killed most of my dwarves, and I lost the rest to a tantrum spiral.
I left generation running a bit. Turns out the Kobolds developed space travel and flew off to the stars, and The Wheel of Cheese remained conquered by the Aliens, until they dug too deep and were killed by Demons. Then the Demons developed space travel.
I regenned later and played a regular game with no future tech at all. Fuck that noise.