game design - How to determine the amount of experience needed for leveling up

Related questions under this topic might include:

1. How should I base how much experience points it takes to get to the next level?


2. What factors are involved in this?



3. How do I keep the player not entertained long enough till he levels up?


4. How can I vary the way the player gets experience points?

Answer

Generally speaking these are done as vaguely exponential curves. http://kol.coldfront.net/thekolwiki/index.php/Advancement#Advancement_Requirements_Overview shows the formulas for Kingdom of Loathing, which are pretty standard for the MMO genre.