A future unknown
Ability scores determined the following way: roll 4d6 drop lowest, do this 6 times, count the amount of bonus of those scores and re-roll everything if that bonus is below +5.
All races and classes from the player handbook can be chosen with the following adjustment:
Humans gain 4 times a +1 bonus to Abilities of their choosing. The +1 bonus may be applied twice to the same ability score. Humans also gain a skill or tool proficiency of their choice.
Players that are at lower level than the highest leveled player can gain Experience Points and levels by expanding gold and time.
It is the same as leveling up during downtime rules (see DMG, page 131 Training to Gain levels). But the player can expend gold to gain the required Experience points.
Current rate is 1 GP = 1 XP
The Maximum HP increase from leveling up is determined the following way: roll the Hit Dice associated with your gained class level twice and pick the highest roll.