A long, long time ago... in a galaxy far away... we had guild stat modifiers. This meant that when you joined any guild you gained and/or lost stats based on that guild's preferred stats (from the help file). While I'm not really a fan of flat modifiers like this, the idea strikes me as one that could have been done really well.
To outline: If every Xth level gained there was a chance of raising and/or lowering your stats, based on the presumed actions of your guild it would simulate aging to some degree. So for instance, if it were determined that tinkers use dexterity and strength primarily to the detriment of reactions and intelligence a tinker gaining X levels would have a chance to gain some small amount of strength and/or dexterity, and the same chance of losing some small amount of reactions and/or intelligence.
Just a random thought based on a mighty old system that no longer exists. I think it might be interesting and enjoyable. Anyone have any thoughts on it?
