Something that's fast paced and easy to play would work, one hard part in making p2p gambling games succeed is to have active players or games up for most of the time so new users would be able to try them.
I imagine that p2p products will only be attractive to players if/when there is some degree of house involvement. I.e., the house can match bets if there are nobody else taking the bet within 10 mins, etc.
Bitdouble did this when they had coinflips on their site, bots would automatically create games and wait for users to match their bets. Unfortunately they closed down after having issues with their site. Yep.
I find that a lot of csgo gambling sites are extremely popular, and are mostly p2p oriented. Yet bitcoin counterparts that offer the same types of games struggle.
It honestly comes down to somewhat of a foul play by the house - I wouldn't doubt that over half of the more popular csgo gambling sites either had insiders betting on coinflips or had bots join them when nobody else would, essentially bridging the liquidity gap.
Of course, there's a conflict of interest there and it's hard to justify. But punters find this attractive, some how.
Also, the game mode is extremely important - something like coinflips are extremely popular while something like binary options that takes a while and is relatively slow doesn't fare as well.
