Why?
Not trying to be witty here (no more than usual, at least), but it seems to me - and yes, this is entirely subjective, but there's little objectivity in this industry - that FPS are probably the hardest genre to compete in, and I'd assume they're kind of... tedious to work on. It requires so much work to come even close to what is considered "standard" there that it seems like it'd be tough and not fun at all to do.
So are you using innovative, new mechanics that really change things up (and can be seen at a glance and explained in one sentence)?
If not, then, well, let me know what I'm missing about this genre.
I understand that the process of creating such a game itself could be valuable and fun for some, but I can't imagine that being true for a long time, working on something for so long just for yourself?
Also, let's be honest here, weapons kind of suck. But then, that's something everyone agrees on.
Alternative thread title: "Appeal of the manshoots"
