Would something like Gameful fit the bill? It's a community to foster the creation of games which are beneficial to humanity. I thought that Urgent Evoke was a great idea, and want to see more in that spirit.

Of course, you might call games a mechanism for your cause, but if your cause is to generally "make it fun to make smart moves in the interest of humanity", or "help people overcome irrational disincentives toward Pareto improvements", then making and spreading games like this is a good strategy. And definitely fun!