I see what you are trying to go for, but I don’t think purposely trying to find something new in a FPS game just to change Roblox’s reputation will get you far into the development of the game.
If you want your game to attract people outside of Roblox, you would need a lot of advertising to take your game to that level. The thing is, I don’t think any Roblox game have ever reached that far, even with the small teams. (Adopt Me, Arsenal) I see how you would like to change that. But, if you’re just a single person working a game that wants this game to go outside of Roblox’s bubble, I don’t think it will happen.
You first have to think about the people who already play Roblox. You have to create a game that attracts FPS players (people who play Arsenal, Phantom Forces, etc.) and beat your existing competitors. How do you do that? You create something new and fresh, but not through innovative game mechanics. Ideas come and go, you can’t force yourself to make a new and cool idea that will blow everyone’s minds. It is really hard to do that when there are alot of FPS games out there that try to do the same thing.
As I said before, I think the design of your world is what you should focus on to make your game stand out. Plan and make a deep and interesting lore (only if you have an idea of what it would be), design cool looking guns, all that stuff. Then, when you have your world in place, you can start thinking of ideas how the game will work. It’s ok if the game is just a team deathmatch. People will still play. Now, when you release it, you will receive feedback and ideas from people who play your game. This is where you can add more content and maybe that’s the point where you can find something new. For example, Fortnite was originally a single-player story game, but when they dropped the Battle Royale mode it just blew up and took it to a place it never expected to be when they were initially developing it.
(below is just a bunch of quotes I learnt from more experienced people in life)
To sum things up, don’t reinvent the wheel, just re-align it, and maybe you will find something worth developing. If you just think about the expected success of your game, you will be disappointed when you actually finish it. Making a game is a like roller coaster ride. You don’t know where it will go next with its twists and turns, but it’s fun nevertheless.
Last quote to make everyone cringe: “Make a game that you are proud of, not a game that will impress everyone but yourself.”
(end quote bottom text)