As previously discussed, levels are obtained in a Roll to Advance scheme. Essentially, everyone earns one experience point per session and then rolls against a target number in order to level. Earned experience points modify the roll, as does race and class.
The original inspiration for this system used a D20 to make the roll. However, I feel this leaves way too much variance in leveling up. Let's take a quick example:
Let's say Bob needs a 25 to advance in level. First, he must adventure for 5 sessions in order to gain 5 experience points, at which point he has a 5% chance to hit a natural 20 and level. Upon each additional session, he gains another experience point which results in a further 5% chance to level (he now needs a 19 or 20). What this system does is to require 5 adventures and then a further 1 to 19 sessions in order to level up. That averages out to (very) roughly an additional 7 sessions to hit the target number.
That is way too much variance and just too many sessions to level up. Instead, let's try a smaller dice size, the D6.
Similarly, Bob needs an 11 to advance in level (5 higher than the maximum roll on a D6, same as the previous example). Again, he adventures for 5 sessions, at which point he now has a 1 in 6 chance to level (~13%). Now, he needs an additional 1 to 5 sessions to level, with the average being 2 or 3 additional sessions. So Bob is leveling up after an average of 7 sessions rather than 12. I think that is much more appropriate with less 'swing.'
Ok, so let's recap:
Experience and Leveling Up
At the conclusion of each session, every player receives 1 experience point. He then rolls a D6 and adds his experience points and attempts to hit a target number based on his class and race. If he hits the target number, he levels up. Any experience points used as a bonus in order to obtain the target number are expended, any unused points are retained. If a player fails to hit his target number, all experience points are retained as well.
So here are the baseline target numbers:
Next post I'll tackle racial modifiers, multi-classing, and wrap it all up.