Create a weekly pot funded by the players to compete for. Then payout the pot to the highest on the leaderboard each week/day/ whatever. Reset and repeat.
Nostr isn’t addictive. It’s facing the harshest competition for mindshare and attention ever created by humans.
It also takes work to build/curate your community on nostr. Once you hit an escape velocity it is amazing, but people are use to their content being spoon fed to them. They don’t like doing any extra work to find it.