OOh I did something like this for my Game Production degree as well, except it was in flash.
A few tips I learned from my experience:
Playtest (and get others to playtest) as often and as early as you can. Even if you don't have the game playable yet, try to recreate the design mechanics in a playable form so you test it early and "find the fun". You might even discover some unique game mechanic you didnt consider while playtesting.
Also also, if you are doing it in a team setting like I am, make sure the flow of assets and determination of duties is concrete. Our game suffered because while I was the lead designer I also speant weeks working on a physics engine that wasnt finished in time for implementation and thus didn't finish nearly as many level designs as I could have which resulted in a far shorter game than we wanted. (Also because alot of the level designs relied on said unfinished engine)
Also Also Also, do not outsource parts of your project to people outside of your group. Unless they are like personally invested into your success (like a parent or whatever) their priorities will not always align with your groups, and if they are not benefiting from the grade, they will have less motivation to deliver product on time. Unless you pay them but I don't know if your school allows for that (ours didn't). We ended up having to use the roughdraft cutscene sketches for our final game release, it was the most painful thing I had ever experienced.
Anyways, these things are always fun, if frustrating, and always rewarding. So how long do you have? Is your school forcing any specific release cycle (alpha,beta,gold), or any development methodolgies(scrum meetings, sprints, etc)?
Unity is great for making things quickly but I found it too limiting for the kind of stuff I am currently working on. But man having to program your own graphics, even with the help of libraries, makes you miss preprogrammed engines.
