So I kind of feel that I want to discuss and get everyone's opinion on One Time Events and what you can do with them for a game -
Now in most games One Time Events go a bit sideways due to the idea of clustering everything into one zone, this could be seen when guild wars 2 did the event with the giant crab things and the servers went to hell with the number of players just trying to cluster into one zone for the rewards of an event that was being crammed into a very short amount of time.
However, these events are something that makes a game special. The stories that happen during these events aren't something that could happen in someone that gets repeated every day in-game. For example, we could see an Invasion by an extra planar or alien force, this would be city wide and could be something with many micro-events scattered everywhere to reach the best outcome players need to avoid say going just for the massive rift or spaceship but rather spread out across the ground and do the job to save the city.
Now as we are using a Single Shard with it creating mirror shards if the population is to high (I think thats close enough to being correct in terms) The issue you run into is that the event can occur differently, so it would be how does a dev team pull off a big event when its a single world that the ending effects, You could make it so different micro events (none the same in terms of location) occur on each shard and thusly could scale to the population or have a set scale. Though you could always have a few zones that force you into a (area only shard ?????).
Do you think its worth the risk of One time events guys ?
Furthermore, It could be a very interesting plot point to run with if you tell players in advance that they could expect the choice to kill off their characters (lets say its in exchange for some sort of epic story reward, maybe you get your own little 2 inch plaque for getting yourself killed blowing up a ship or something)