Is developing a BTC gambling websites considered to be profitable?
If you are developing the site by yourself and with the help of your friends so you don't have to pay for this in advance then at least you won't lose much if the site doesn't work.
Can I expect people to pay attention to a new game?
If it's really unique like you said and you'll launch a Sig campaign to attract players to your site, why not?
Is the market maybe already saturated?
No, it's not saturated. New gambling sites appear almost every day. Most of them disappear soon after the opening, but some of them become popular and successful.
Good luck with your project!