Races: Only races from the Player's Handbook are allowed with the following exceptions and notes:
Dragonborn, Tieflings, and Drow (Dark Elves) are very unusual and will be met with stares and/or discrimination everywhere they go.
Orcs are allowed as a player race – though they will be met with some suspicion in certain “civilized” towns.
Goblins are allowed as a player race – however they are highly unusual and generally hated by everyone.
Variant Rules: All variant rules in the Player's Handbook are allowed – with the following comments:
Equipment Sizes (PHB, p.144): Using armor of a different size is allowed without modification. However, a day of this will incur one level of Exhaustion (PHB, p.291).
Some variant rules from the DMG are also used. (Need a list)
Significant Injury Houserule: When a character wakes up after being unconscious, they acquire one level of Exhaustion (PHB, p.291) if they failed at least one death saving throw while unconscious.
Unconscious condition: Ignore the last bullet point: “Any attack that hits the creature is a critical hit if the attacker is within 5 feet of the creature.” Such an attack may or may not be a critical hit based on the normal rules for critical hits.
Grid-based combat: Combat is almost always done on a square-grid battlemat with miniatures or other tokens.
Persistent Damage: (see below)
Wizard enhancements:
Wizards can put spells in their spellbook even if they are of a level higher than they can prepare.
Wizards can use Ritual Casting to attempt casting spells of a level higher than they can prepare. To do so, they must spend an additional 10 minutes and make a spellcasting ability check (just like for a spell scroll) for each level above their maximum. Any failure results in something bad (TBD).
Deities: The preferred deities are from the “Fantasy-Historical Pantheons” (PHB, p.297-299) or the Non-Human Deities (PHB, p.296)
Level Advancement: Players can expect their characters to advance levels slowly. Expect to be at first level for “a few” sessions – and do not expect them to ever reach double-digit levels. (Unless I change my mind)
Economy: A quick rule-of-thumb is that one gold piece is equivalent to $50 in real-world spending. Thus, a Longsword costs $7500 equivalent (and is therefore considered an expensive accessory).
Languages: Not everyone speaks Common, but everyone has a native tongue. (Needs expansion)
Flanking: Let's try using the DMG Optional Rule: Flanking (p.251)