My next suggestion for how to make City of Titans a new standard for MMO's is to have the game change based on day/night, lunar, and year cycles. There would be cosmetic changes, such as trees blooming and losing their leaves, changes in weather, NPC's changing clothes, hot dog stands being replaced by ones that serve hot cocoa or lemonade, or stadiums becoming inactive for their respective off season. There would be holiday events that give fun mini games periodically, but I am talking about something much more interesting. I am talking about the missions and zones themselves change based on different cycles. Here are some examples:

Day: Bank, jewelry story robberies, artifact goes crazy at museum, biology student mutates into gorilla/crocodile hybrid
Night Vampire attacks, alien abduction, poltergeist activity, movie in the park disrupted by rampaging dinosaur

Full Moon: Werewolves, astronomy class at University taken hostage
Half Moon: Cultist ceremony in graveyard
New Moon: Wererats, Cat burglar breaks into penthouse (less light at new moon)

Spring: attack on flower festivals, someone trying to ruin a big spring ball game, fairies enter our world through portals
Summer: ice cream factory held for ransom, ice wizard attack that turns city into winter mode for a few days
Fall: rogue hurricane hits, disruption of elections
Winter: frost giant incursion, sidewalk salt trucks stolen, people stranded by blizzards

In addition to this there could be super secret rare events that only happen once a year. The equinoxes and solstices could be the trigger for occult mischief. Friday the 13th would cause a powerful boss to spawn and start attacking people at Titan University. There may be a comet that comes around every July 16th at 12:12 EST. On a leap day there may be a full scale alien invasion that would last a day. This secret content would give a sense of mystery to the game.

Overall this system would mean that every season you would want to go back to old areas and replay them because they're different now. This would be a wonderful way to keep the game fresh and interesting.