I think I can do this one.
27 square miles of grassland 
Regional lake and/or rivers 
2 miles of coastline 
4 square miles of marshland 
20 Square miles of mountains to surround my land on three sides 
100 Loyal soldiers 
Village of 50,000 
School with university-level education 
Alchemy Lab 
Industry and Port 
Center of learning, bitch!
The militia of 100 will be enough until I can get a couple war golems ready to go. From the 50,000 people, I can easily get a dozen or so working to increase that number after I teach them the how-to's. The mountains will supply all the stone or clay I require. Any major breakthroughs, I'll keep to myself.
The alchemy lab will be stocked from the marshes, and I will once again take the lead with a group doing our best to learn all we can. Again, any juicy discoveries I will keep personal.
The industry should be able to be self-sufficient without me, and the clinic will require more specialized souls.
That's where the school comes in. I'll be the Dumbledore of the fantasy world, but with science. All the knowledge I have collected, I will teach and train the next generation to keep it going, and my land should eventually be able to be completely self-sufficient, profitable, defended, and centuries beyond any neighboring states.
While my people can't be outnumbered heavily in this CYOA, and they have backup with potions, golems, a wartime industry, and cybernetics should we take casualties, there's one glaring flaw.
If another player is some kind of demigod that spend all their points in powers and has no purpose other than being a dick, I don't think I could hold off an invisible shapeshifting telekenetic earthquake-causing lightning-spewing lich dragon in power armor.
But I don't think too many nations could hold that off anyway, so I'm not heartbroken.