At Tobold’s suggestion, I have been trying Shop Heroes, and I think Recettear converts to a mobile/social media game nicely. Why be an adventurer when you can be a shop owner selling things to adventurers? In the inverse of normal MMO mechanics, it is the adventurers who buy random crap, and they buy a lot of it because most of it has a 5-10% chance to break every adventure. Strangely, they do not actually use equipment you sell them, but rather you sponsor their adventures by equipping them with goods from your shop. Those items they break.
I would like to highlight the game’s City upgrade mechanics. I am not high enough level to see what it does in the late game, but it immediately seems to encourage players to be pro-social in a variety of good ways, while also making the high-level players’ drive for advancement subsidize the low-level players’ development. It does undermine the permanence of social bonds, which may be a good or bad thing depending on your view of this sort of thing.
The City is the equivalent of a guild hall, and it starts with a few buildings. Some of them help you get resources, like a mine for iron. Upgrading it increases the rate of iron provided. Upgrading your town hall expands your City, both in terms of population and getting new buildings. New buildings provide bonuses like new adventurers, bonuses to them, crafting bonuses, and raising the level cap on your crafters and adventurers. Those bonuses are effective for a limited time after anyone invests in building upgrades, 30 minutes for a minimal contribution up to 24 hours for a full upgrade bar. City members’ contributions are broadcast to all members, with an overall contribution rating on the member screen.
While there is an obvious anti-social incentive just to leech off others’ contributions, there are a variety of pro-social incentives here. If you want to raise the level cap for yourself, you contribute to the team. If you want to activate bonuses for yourself, you contribute to the team (even minimal contributions add up). Beyond mechanics, there is the social incentive of receiving public credit for contributions, along with the implicit social obligation to contribute to the team embodied in that members screen. That can turn nasty, in the way some MMO players consider a low gearscore to be leeching, although it also promotes reasonable stratification by player type if hardcore players who contribute a lot end up in cities with other hardcore players who contribute a lot. I would also expect to see social cities, where a few workhorses power their casual friends.
The last detail: your contributions go with you if you change to a new city. Wow, that’s big. Have you ever contributed to a guild only to be the last surviving member? Given it your all and had to abandon your sunk costs? Shop Heroes has no guild sunk costs. If you want greener pastures or to switch to a friend’s guild, you bring your investments with you. If you kick someone out, s/he takes her/his investments too. That might make someone hesitant to kick a toxic but rich person from the city, but I have yet to find how to be toxic in this game. Chat is hidden by default, and we are all off in our own shops.