World Rules

Just a wee tab about what you can expect in terms of rules;
-the big one...the world will react to you. if you go around being murder hobos, the town watch will be called, investigations will be conducted and eventually they'll work out you killed their storekeep because they wouldn't give you a priceless artifact for half price. they will hire bounty hunters, you will be outlawed and the kings, dukes, merchant guilds, corporations will try damn sure to kill you...don't be stupid.
-Similarly for clerics/paladins/warlocks (anyone who gains power from another being etc) you will have to follow said beings demands etc or lose your power. for example if your god is Helm and you fail to protect the innocent, your spells may be weaker or straight up not work. conversely if you convert many people to their worship, you may be able to ask them for greater help.
-Inspiration bonuses will be handed out for roleplaying your character well, e.g this will be in the form of a d12 you can add to any saving/combat/ ability roll once per inspiration.
-if you're character is knocked to 0hp they must roll a Con Save against Half the damage which knocked them out e.g 12 damage takes you to 0 con save is 6. if you fail roll a d20 against the lingering injury table.
-Long rests will be a lot harder to come by, so you'll have to plan accordingly. I.e you can't go for an 8 hour nap in the middle of a cultist temple....sorry
-Ammunition is counted-you can retrieve 1d8 worth of arrows/bolts/shot from every battle. during your downtime you can make more ammo or you can buy it form certain stores. depending on what ammo you're carrying you can carry up to 2 full quivers at a time. certain magical weapons may not need ammunition, you can also buy/ craft yourself bigger quivers within reason.
-Lighting rules apply, if it's pitch black and you don't have darkvision attacks against you have advantage and you have disadvantage on attacks against others. any saving throws that require sight automatically fail. Torches are your new best friend.
Cover rules apply-if you've got a low wall, a tree trunk, other people.... in front of you that's half cover, you get +3 to ac and dex saving throws. if you're hiding behind a full sized wall etc you get full cover and can't be directly attacked. cover only works for attacks coming from the other side of cover.
To speed things up your characters may already know certain things, basic world knowledge is readily available to everyone, specific backstories might be able to inform you in greater detail about things.
-for things like perception, investigation etc only the first character roll counts. exceptions may count on case by case basis.
-if you realllllllllyyyy can't let go of your favourite character from a previous campaign, they may end up in Vaelun by Planar travel but naturally they have no friends, no family, no associates or contacts so will have a few disadvantages....

On a critical attack roll, you will do max damage for each die + modifier + another damage roll e.g if you do 2 d12 + 4 you would do 24 + 4 + 2d12 damage

*Trialling a few new rules, if any become an absolute pain they may well be removed.