This is the solution I came up with, but there is still a problem: Regular Tibia skills (sword/club/axe, dist, shield etc.) don't work well with no vocations.
Now you can either make them more modern, with Vitality/Magic/Agility/Strength/Dexterity/Intelligence/more/attributes but this clashes with items giving stats, will be a nightmare to balance and you have to implement some kind of progression or skill point system and you have no idea if it will even be fun or simple enough for players. Or you use the old skills for other systes like mining or crafting but then what's the point of gaining levels?
Either way I think we're onto something