Hello, I'm creating a generic educational RTS as my thesis project, and I'm using the Unity Engine to do so.

By saying "generic educational RTS", I mean that it's gonna be an real-time strategy game where players will be able to earn money, an in-game resource, by answering questions on a school subject provided by the instructor by means of external XML file. They will still be able to collect other types of resources just like a traditional RTS, build buildings, and manage their city's economy, similar to the old "Caesar" series, or the newer "Banished", or "Cities: Skylines" games. Money will be used as an additional resource requirement for performing different actions such as building, upgrading, whatever. Also worth noting is that any form of combat will not be present in the game.

I've build the basics like UI, buidling placement, etc, however what I'm struggling with and would like some input on has more to do with the game's visual aspect, and more specifically the "era" that it's gonna be set in. I personally really enjoy the more medieval or fantasy settings, however that would also mean additional complications in the code, as I would also have to build an AI for the townspeople which would include pathfinding, action priority queue, etc, along with finding models for them and possibly animating them as well if they aren't already. On the other hand if I create something like "Cities: Skylines" that complication is lessened, however so does the extra depth of creating a more advanced system.

It's also worth mentioning that I'm creating this game on my own, and time is of the essence, meaning I won't have too long to build this, about 4-5 months while also having to do uni work, so please keep that in mind.

Therefore I'm making this post to get some input on which "era" I should have the game set in or anything else you would like to suggest, while also taking into consideration what's more appealing to teenagers nowadays, since they're the target audience.

Thank you.

It's also worth mentioning that I'm creating this game on my own, and time is of the essence, meaning I won't have too long to build this, about 4-5 months while also having to do uni work, so please keep that in mind.

Using an Agile methodology is probably your best approach here. Figure out what the absolute minimum viable game is and work on implementing that as fast as you can. Once you have a functioning game then think about what small features you can add to make it better and implement those. Rinse and repeat until you hit the deadline. The key point is that at each step of the way you'll have something that is "shippable" -- it might not be everything you'd hoped it would be but at least it's something you could submit if you had to.

This sounds like a game we played in world history class. Your grade was based on your class work or rank in the game.

My suggestion is to do a future era if its a straight rts game with no reference to world history. This will give you complete freedom in design and leg room on some of the mechanics.

Some thoughts moght be a game around the idea of colonization of an off world. Robots controlled by remote control or there was a movie out a while back with the guy that played the main character in die hard... can't remember his name.
Basically you sat in a chair and plugged in to a feed that let you see, feel, and controls an artifical being. Oh like the movie avatar.
All AI would be robots and would not have the expectaion of acting with life.