I was working with Klang Games on MMO persistent world simulation called Seed.
This game is quite ambitious and work on it had a lot of learnings and challenges. Working on persistent world simulation means that almost 90% of the game happens on server that has to handle huge numbers of the players and that means that architecture must be horizontally scalable. Also that means that challenges and solutions for classic game features of this type are quite special in their approach.
My work on seed was predominantly as part of largely independent team where we planned, helped design, architect and implement various game features. Most features had to comply with requirement of scaling to a very large amount of players and also work on AI was very big part of game since the game as persistent simulation requires substantial AI system.