Dwarf Fortress 1.00?
Also, I really want an RPG that could be rando-/procedurally generated game, that let you really influence things, and built everything from parts - vehicles, buildings, items, even creatures. Fantasy, modern, sci-fi... doesn't matter.
So, like, you could design a sweet base, installing an armory, storage and barracks and stuff, or maybe a massive palatial house just to show off. All the buildings would be built off the same system, too. Similarly, you could make your own items - pre-existing items basically being the exact same thing, pre-designed - by arranging the parts on your own, swapping out barrels and power sources and magic gems and power sources or whatever you wanted (the thing I always envision with this thing is a giant metal spear-thing you plant someplace, with a big outer casing to keep out weather and deployable ground-latchy things like the Siege Tank has, that acts as a teleporter beacon). It's efficiency, reliability, and all that would be determined, for the most part, how well your design is - though, maybe some kind of skill would play a part in it. Similarly, individual items might be better or worse than the base design, depending on who built it - some-guy with [craftskill] 0, or a master craftsman with a huge [craftskill]. Vehicles might be built with the same system, and you could, say, finding a wagon or an APC or something, and slowly tricking it out with a bigger engines, a rare power source, or just more armor plating or whatever. And if you could get a production center going, you could sell these things to the NPC populace, and it would actually appear in the world.
Like... say, the world starts with normal old iron weapons. You find fictional-element-x, and you discover it makes a better alloy when mixed with iron. You now are the inventor of... mithril, or ToadyOneium, or whatever you want to call it. Now maybe you find some magical crystals. You could make a staff out of ToadyOneium, stick a magic crystal in it, fiddle with some gubbins to so it shoots straight, scatters more/less, and has a more efficient magic-layzer-output, and then get a building full of people to start cranking them out. Suddenly, your town local town has magic laser gunwandthings. If your gunwandthings are easy to make, you'd have basically started the shift of warfare from spears/arrows to guns.
Making creatures out of parts would make it easy to do stuff like make crazy monsters, new races, or body-part-damage. You could modify creatures in a genetics lab or something, adding wings to scorpions or lionfish quills to bears, or make a genetic abomination from scratch ("more muscles! Bigger claws! Holy crap this digestive system I designed is terrible, let's make it better! More arms! Lasers in it's eyes!")... or maybe some kind of super-worm that reinvigorates the world's flora after some kind of apocalypse... or maybe just making the ubermensch, who might eventually take over the world's cities and population... If an arm got hacked off, you could build a robo-arm (with the aforementioned crafting thing
) to replace it... or just to gloat, you could kill whoever did it, take his arm, and use that instead.
I'd also like the ability to organize groups, guilds and factions, and have a personality thing, like DF has, as well... every NPC you meet would react to you based off of it. Depending on personality, kings might rather go to war than negotiate peace. Small factions would exist in the game - unions, guilds, like I said. A given group could be anything... Robin Hood's bandits, a cabal of conspirators, bloodthirsty thugs, a neighborhood watch, maybe an independent adventuring party. You could ask any of these dudes to join you or work for you or whatever... every NPC has their own stats, and such. ...This sounds pretty much just Future-plans-DF, so yeah.
I guess the TL;DR of it is that I want a super-dynamic world you can see and play in, detailed enough that you can play it through a single character's eyes.