Random generated, fun game for events
I've posted this elsewhere but will post it here too as it sort of overlaps a couple of topics.
There's been a lot of debate over the randomness of the pumpkin drops this Halloween but:
I actually like the idea of having a pure-luck type thing in an event. It's something different.
Maybe don't call it an achievement, and don't make the prize the event currency, and if all players know it's completely random, then it could be an interesting "will-I-won't-I complete it in time" surprise.
Possibly something like when you open a mystery box, every time you login you have a rolling dice that generates a random number that adds up over the event and your total at the end determines your reward, or if you get it at all?