A bit like hide and seek or tag, but instead of “finding/tagging” others, you’re trying to pickpocket them unseen.
Everyone looks clearly different. But you don’t know who is who.
Some players are secretly pickpockets.
When you walk past someone, on a small delay (because of network, that happens anyway), they will lose money.
This is a nice way to “incorporate” the delay/lag inherent to online games. When you think you pickpocket someone, ask the server if you actually did. They confirm (or not) by sending back a message to both players (the pickpocketee and the one pickpocketed) updating their money.
I’d just need to find the actual gameplay for the non-pickpockets and the specific rules. Maybe combine this idea with Saving Grace? Which was about buying the right products from a busy market and also had an option for pickpockets to watch out for?