So, by now, most of us are aware of these achievement things. They're the little things that pop up at you when you complete certain tasks. They're popular in mini online casual games, in console games, and various other things. XenForo have a first step in the right direction for this with trophies, but I think it is not quite there yet.
Have a fully configurable achievement system:
- Post at least 3 threads in each of the subforums X, Y, and Z.
- Like at least 5 posts in each of the subforums A, B, and C.
- Receive at least N likes from the administration team.
Have achievements that expire after some time:
- You must complete these objectives by Date X
- You must complete this task within 1 week of registration (good to make people make that first thread).
Give achievement specific user titles / user groups:
- Get larger avatar quota for completing this achievement!
- Get unique user title for completing that achievement!
Now, your user have incentive to be addicted to your forums and post lots, AND have bragging rights as result of completing the specific achievements (that the new kids now cannot get). Anyone up to make some serious forum addiction?