C#/Unity top-down 2Dgame newbie advice

Hello Unity Community!

I'm new to this forum and actually this is my 2st time posting at a forum, so if i make any mistakes please excuse me and correct me so i learn. Sorry if my english is bad but i'm trying my best!

Hmm, let me explain the situation: I'm a student in Computer Science and i will work another student at our graduation thesis : a C#/Unity game! We want to make an Online-Multiplayer top-down 2D with capture the flag concept (2 or 4 players). We have a deadline until March, about 5-6 months. So, because it's serious project for us, i will be asking severals questions about this so you can help us! We want to read books/go through tutorials, learn and start creating as soon as possible.

We are almost sure that we are going to use Unity as our game engine. My first questions are: 1. Is a game engine necessary for our project? I mean, is it really gonna make our lives easier or harder? 2. If we ll eventually use Unity, what is the best way to start? Start learning about C# game programming basics or learning about Unity game programming ?

Any suggestions about any good book for begginers or tutorials or documentation whould be really helpfull as we dont have any experience in both C# and Unity?

I know it may be difficult to give us straight answers here, but we would really appreciate an opinion from anyone experienced in C# Game Programming!

Thank you all in advance!!!