An RPG-faucet game. If it gets fun enough, people will visit and use earnings to grow rather than to withdraw.
Now we're talking, An RPG Faucet game could incorporate a forum as well where you could discuss stratergies (Combining 2 ideas Forum/Social Networking site & an RPGFaucet game).
What type of theme would you suggest? Are you thinking of something like Clash of Clans or a text based game?
In my last project
www.miningforfree.com I tried to introduce a game style to it, but after a while even a click and collect game gets quite complicated in terms of keeping track of coins accumulated, referrals earnings, even the user management is a complicated process.