Our Roll to Advance alternative experience and leveling system uses a die roll for variability. This adds a bit of unpredictability into a system that would otherwise have characters automatically leveling up after X sessions at a certain level. We chose the d20 for our standard system incorporating all the advanced classes and races because the small difference (5%) between each result on the die and larger target numbers allowed for more differentiation between classes and races. We experimented a little with the d12, and though I suspect that this might be the sweet spot compromise, but we settled on the d20.
We wanted to roughly approximate the relative progression speed of the original games (though we did substantially adjust the cleric), and we wanted to maintain noticeable, if minor, differences between various race-class combinations. For example, we wanted the ranger to be slightly slower to advance than the fighter, while the magic-user was to be slower still. Meanwhile, racial modifiers were also present, with the dwarf having a slower advancement rate than the halfling, but being quicker than the elf. And it wasn’t only the starting target numbers we looked at (17 for fighter, 18 for ranger, and 19 for magic-user), but the rate of increase. For instance, the druid and illusionist both begin with an 18 as their target number to advance to second level; however, while their numbers are very similar, the illusionist slowly becomes a little tougher to advance as the levels increase. The magic-user, on the other hand, starts with a 1st-level target number only one higher than either, but the rate of increase is slightly larger than even the illusionist. With a d20 and larger target numbers, these sorts of differences were relatively easy to work in, and I think we did a fairly decent job of mimicking the original scheme.
However, the d20 variability does create a good chance of widely-spaced levels between characters who have played the same number of session, particularly at lower levels. At higher levels, where the target numbers are much larger, this variability tends to disappear as the number of sessions played begins to matter much more than the result of the die roll. However, how many of us really spend a lot of time gaming at higher levels? I know that we don’t. In fact, most of our gaming over the past few years has been in the levels 1-3 range, and I consider levels 4-7 to be the range that gives the most bang for the buck, so to speak. I’ve spent relatively little time gaming at name level (9th) or above.
Another consideration for us personally is the fact that our Wizards & Warriors homebrew game has only two classes and one race. The need for small but noticeable differentiations between multiple races and a wide range of classes just doesn’t exist. Our original plan was to stick with the d20, but additional thought has led me to think we’d be better off with a smaller die and smaller target numbers to cut down on the odds of wide gaps between character levels within the same party. It’s bad enough to roll badly during a combat while everyone else at the table is tearing through the enemy; it would be far more disheartening to roll badly a few sessions in a row and find that your 1st-level character is now running around with a bunch of third and fourth level characters. My initial thought was to go with the d12, but a post over at of Pedantry and further reflection and experimentation has led us to choose the d6. Besides, an oldschool rule of thumb should be “when in doubt, roll 1d6.”
So here is our current plan for Roll to Advance in our two-class homebrew game, presented as an example of how the Roll to Advance can be quickly and easily adapted to whatever sort of game or style you want to play.
For instance, we’ve decided that, though we firmly believe PCs should start at 1st level, we don’t necessarily want to spend a long string of sessions with them stuck at 1st and 2nd level; rather, we’d like to see them advance rather quickly through the first few levels, slowing down once they reach 4th (hero) level to maximize the amount of playing time in the “most bang for the buck” zone. So characters have a 50% chance of advancing to 2nd level after just one session (counting the XP they will earn for that session) and a warrior could theoretically advance after each of his first three sessions if he rolled sixes at second and third level.
A note about the uneven-looking progressions: We started with nice even rates for each class and a nice relationship between the rates for the two classes. But running them through a 52-session simulator didn’t give us the results we really wanted. After first unsuccessfully trying a massage the nice even rates into different nice even rates that got us what we wanted, we gave up and began tweaking each number at each level for each class independently. I had cooked up a spreadsheet to show us actual session-by-session results and could look at lots of simulations by quickly refreshing the sheet and watching where advances were likely to occur and how the two classes compared to each other. We kept playing with the numbers until the simulated results looked like we wanted them to and didn’t bother worrying that they aren’t really very “smooth.”
Basically, you can subtract six from each target number to see the absolute minimum number of sessions that will need to be spent at each level before advancing. A warrior who always rolled a six would reach 8th level after his 48th session, or nearly a year of weekly play. A wizard who always rolled a one would reach 6th level after 49 sessions. So with even the most extreme difference possible, the results seem (to me, anyway) to be perfectly reasonable. My simulations show that a typical result after 52 sessions of play will be a warrior well into 7th level (getting close to 8th) and a wizard that has just advanced to 7th level and has a lot of adventuring to do before he gets close to advancing again. The two will have spent most of the time at equal level or with the warrior one level ahead. Once in a while the wizard will be two levels behind the warrior, and in a few instances early on the wizard may even be a level ahead of the warrior.