Greetings. Thank you for opening this thread. Long post ahead. I am a High School student trying to get into game development. I would like to ask you a set of questions, but I think giving a context first will be the best. So, this is what's happening:

In recent time, about 3 weeks ago, I started learning how to use Unity Game Engine and Blender. I always loved to draw and design all kinds of weapons, armors but also levels (unfortunately, all of those are on paper only, FOR NOW, of course) and when I started to think about how to apply this trait of mine, I concluded I could try creating a game. Since it's only been three weeks, my game-making skills are extremelly poor (as expected). Fast forward to yesterday. We were supposed to pick up a topic for our graduation thesis which we will hand in closely to our school-leaving examinations in year 2021. There is a TON of stuff to choose from. As long as it is part of IT, it's fine. And I chose to make a game. Well, it's more of a one level of a game in my case. More students before me have taken this topic and passed totally OK with Flappy Bird-style game they made. They were satisfied with it. I wouldn't be. I want this game to be best possible, that is why I also want to start working on it as soon as possible. In fact, I am starting right now, but I figured it would be better to ask here first. I have roughly 17 months to make a game worthy of passing. Of course, it could be some Flappy Bird. But I want to go further. Excuse me if this all sounds stupid, but I simply would not be satisfied with just any game I would make. I am well aware I won't be able to make a game like Battlefield alone, that there is a ton of people and budget behind such games. But I want it to be as best as possible.

Now, my question is: What kind of game would I be able to make in this time of 17 months ? You have probably rolled your eyes after this question, don't worry, I understand how subjective the answer is. But I will at least try to state some metrics that can help with answer. I believe I have some fundamentals of programming, willing to learn the language needed (I believe in this case it's c#), I will be hooked on creating, animating and further improving 3D assets as needed for sure. I am able to dedicate at least 2 hours every day, a lot more so on weekends. I have to prepare for school and I also work, so that would be 2 hours of time on workdays right now. I would be able to get music and voice samples for characters in the game. 

Here is my current plan. Please, if you see this as unreal to make in my deadline, tell me about it. I want to make one level of a FPS shooter, kinda sci-fi game with approximatelly 4-5 cutscenes and a small bossfight at the end of the level. Graphical quality would be that of a current CS:GO. Favored play-time would be, I think, around 15-20 minutes. Map would be a destroyed urban area. I have a lot of concepts (characters, weapons, rooms and so on) already drawn and if not, envisioned. If this is not possible, what would be the best game I would be able to make in 17 months ?

Thank you for reading. Please, be honest. I know my idea can sound stupid, and answer I am looking might seem too subjective, but I want to get corrected if I am wrong with all of this. I highly value any reply that will be able to help in the slightest.

Until then, have a nice day.

41 minutes ago, Rutin said:

... if this is your first game and you're doing it all from scratch including assets then it is best to keep it as simple as possible and polish up at the end. 

Thank you Rutin. I find your reply of great help. May I ask: What exactly do you mean by this part I underlined in quote ? I don't want this to look rude, I just wanted to ask you about this part of your reply specifically.

Most people vastly overestimate what they can accomplish.

I've helped with high school groups as one of their professional contacts for a course. They create a course project, and over the school year they create a game.  Every single year the teachers and the professional contacts advise them to do less.  Have simpler worlds. Have simpler models. Have simpler gameplay mechanics.  They turn it down, and we tell them "do even less than that".   The school year progresses, they reach the end of the year, and as the project crunches to a close, they realize what we meant by doing less.

I personally recommend doing a series of one month projects first. Learn what you can accomplish by yourself in a single month. When the month is over, evaluate it, dump the project, and do a completely different project for one month.  Repeat this for several months and you'll quickly discover what you can actually accomplish. 

It is far, far better to have a very simple mechanic that is simple to implement and yet fun, and then spend your time polishing the game by adding better menus, graphics, audio, and effects after it is figured out.

frob said:

… It is far, far better to have a very simple mechanic that is simple to implement and yet fun, and then spend your time polishing the game by adding better menus, graphics, audio, and effects after it is figured out.

@frob I'd go as far as saying it's often also more fun to apply polish and extend a simple game than it is to work against lots of goals that need to fit together to create something enjoyable.

@n1h1lu5_k start making a 2d flappy bird in unity, since C# and unity already seem to be your favoured tools. See if you can keep it within a month, then start over (perhaps with another flappy bird game, tetris, missile command or space invaders)
When there is around a year left, you can consider the scope of what you'll be working on. With the experience from the 1-month projects, you'll be able to better estimate what you can do. I'm not saying that it's impossible to make an fps within a year. It's very reasonable, but it very much depends on how much work you want to put into it - how many things should your application do?

Some reflection from someone who once signed up for a gamedev project in school; I spent nearly half of the time writing my own GUI, and the other half painting sprites. Whatever was left was a report with a big discussion chapter, explaining why I couldn't manage to deliver in time. Don't be stupid like me - use placeholder art and existing libraries for stuff that's been done before.