You gave virtually zero information about the project (other than, it's a first-person shooter, and unimportant theming information).
You also gave no information about your skill level, how many people are on your team, their skill levels, how large a budget you have, how much time you have to develop it, and so on.
There's not enough information to answer your question.
Is climbing a mountain feasible? Sure, if you're an experienced mountain climber, with the correct equipment, and if the mountain happens to be small, and if the weather is favorable. Is it feasible for me? Nope! :P
Since we don't know what mountain you are talking about (other than "first person shooter involving tote adorb kitties"), and we don't know what mountain-climbing skills you have, or what the weather (budget and timeline) you're talking about, then I doubt any of us can answer the question properly. :mellow:
Instead I'll try to help by asking you some self-reflective questions:
- How many games have you made before?
- Compared to your previous game, how extreme of a jump is this new game going to be to develop?
- As far as the stepping stones of games go, getting you from the present to your eventual long-term goals, is this project the smartest next step for you, or are you trying to leap too many steps at once?
- Are ready to make this game skill-wise?
- If you need help (3D models, animation, music, programming, etc...), do you have the money to pay for that help upfront (not in fantasy "profit" sharing)?
If you answer those to yourself, it should also give you better insight into answering your own question.
Sometimes the answer is, "I'm ready; let's do this thing". But more often the correct answer is, "Let me slow down and go about this more methodically"
If that second answer is the case, then no worries, here's my advice: Many creative individuals have been forced to work under limiting circumstances, and often find that the limitations help their creativity shine all the more.
So my suggestion is, first figure out where you are at (skill-wise) and what you have available (resource-wise (time, money, free help)), and then decide what you can within the boundaries of your known limitations, and how far you can stretch them to create something incredibly impressive despite what you are working with.
Basically, instead of saying, "Here's what I want to do next, can I do it?", I suggestion, "Here's what I have available, what should I make?"
Hopefully that's of some use to you.