This is an example of how the matter is handled in Mythus. At what age one’s Heroic Persona starts at under the standard mechanics can range between the age of 12 and 80―in a civilized land it can go as high as 99. If you can’t choose an age then the default is 25’
That age is in Class 4, where your HP starts out with his base STEEP in his Vocation’s K/S Areas. He starts out in a younger class then he subtracts the number of points of STEEP as indicated below. Should you decide that he’s going to start adventuring when he’s in an older class, then he gets a bonus to STEEP that is the bonuses of the older classes added together.
Let’s say that Mardis―a 76 year old great grandfather and scholar―needs to go out on an adventure for the first time to get some medicine for his ailing great-grandson. Being his age he gets another 450 points of STEEP to add to his K/S Areas.
Age Class Ages STEEP
When subtracting STEEP you need to take at least half from those K/S Areas under the HP’s Vocational Trait; The rest can then be taken from either of the other two Trait K/S Areas. When adding STEEP you must add at last half of the bonus to the HP’s Vocational Trait K/S areas, then divide what remains to the other to Trait K/S Areas.
Since Mardis is a Scholar―a Mental Trait Vocation―his player would need to add at least 225 points of STEEP to any Mental K/S Areas he has, with any STEEP left over going to the HP’s Physical or Spiritual K/S Areas. And when it comes to adding STEEP to a K/S Area the increase can only be half of the original. So if Mardis had a base STEEP of 12 in a K/S plus an Attribute of 15, then his starting STEEP would be 27 and his player would be able to add just 13 bonus points to the K/S, for a total STEEP of 40.
In addition since he’s 8 age classes past 5 he gets to add 1 bonus K/S Area for each Trait that he has with a value of 90 or better. That means a possibility of 24 extra Areas at a value of 2d6+Attribute, one per Trait, which means he could have gotten 3 K/S Areas when he turned 36, another 3 when he turned 41, and so on and so forth. Though you don’t have to add them in one big gulp you could add each bonus K/S over the course of the years.
Now to top this off, for every year past the age of 35 the HP gets a 1d10 in added STEEP. But for every year he is under 25 he would lose 1d10 in STEEP. This is in addition to any STEEP gained or lost for being in a higher or lower age class. Considering that Mardis is some 41 years older than 35 his player would then get another 41d10 in STEEP to add to the great grandfather’s K/S Areas. BTW, I added the minus 1d10 to STEEP for each year younger than 25 because I’m mean; Gary was a bit too soft hearted to do anything like that.
When it comes to this bonus STEEP the same rules apply as for any bonus STEEP gained for aging into a high age class. At least half into the Vocation Trait, the rest into the other two traits, and no more than an extra amount of STEEP equal to half of the Area’s starting STEEP.
And just to make things even more complicated, it is my recommendation that you make your adjustments year by year instead of doing it all at once
That’s pretty much how I’m handling previous experience in Mythus, you of course are quite welcome to handle it the way you prefer.
Of course your preferred system would handle matters differently, which leads me to ask; how does your preferred system handle previous experience, or how would you see it handling the matter?