Bonus-action Potions. Potions may be self-administered with a bonus action. Using your full action will automatically maximize the efficacy of the potion (i.e. max roll).
Flanking. Flanking gives advantage to hit, unless the creature has exceptionally high Perception.
Surprise attacks. Surprise gives advantage. Surprise requires an unseen attacker or unaware target.
Meta-combat round. Each round of combat may have a one-minute player phase where meta strategy can be discussed. During combat, collaborating is encouraged via what can reasonably be articulated by a character, but lengthy discussion is discouraged.
Exploration
Jumping downwards. Characters can safely jump downwards 10 ft without taking fall damage. For every x additional feet, a DC x Athletics check is required to prevent fall damage.
Spellcasting
Spell scrolls. This house rule extends spell scroll casting to all classes. The caster must pass a check using their spellcasting ability or INT if they do not have a spellcasting ability. RAW, you can use a spell scroll if the spell is on your class list, and if it's of a higher level than you can normally cast, you must pass a DC 10+(spell level) check using your spellcasting ability else the spell fizzles. This rule extends casting to spell scrolls not on your class list, using a DC 10+2x(spell level) check, which applies to non-casters as well.
Death, Injury, and Massive Damage
Dying Status. Unconscious status is boring, so hitting 0 HP enters you into the dying condition unless otherwise stated.
Roll death saving throws at the start of your turn like normal.
Fall prone. You cannot use movement nor any of your actions to stand up while dying.
You may use your action or bonus action. However, each usage generates 4 levels of revised exhaustion.
Massive Damage. Taking massive damage (>50% HP) may result in a CON save to see if something like a System Shock effect occurs. Taking massive damage that knocks you unconscious may result in something like a lingering injury.
Character Building
Feats are allowed. Feats are allowed in place of Ability Score Improvements.
Multi-classing is allowed. Sounds good.
Ready a backup character. Be ready to roll.
Backpack
Encumbrance & Carrying Capacity. Track normal Encumbrance, but we won't hyper focus on it. Be pragmatic.
Money and Loot. Track your loot. Gold and silver currencies will be used (1gp = 10sp). Other valuable loot like gems may be assigned a currency value and immediately liquidated. Others might need to be actively sold.
General
Quick rulings! We'll make quick rulings for most rule disputes. Make a note of the questions for later, so we can get a proper ruling for future cases.