These are the house rules I use when I run D&D, intended for use with D&D 5e (2014)

Critical hit and failure

In Combat

Rolling a natural 20 will automatically hit whatever you were attacking, you double the amount of dice you would normally roll for damage (for example, if attacking with a dagger which does 1d4+2 damage normally, a natural 20 will do 2d4 + 2 damage).

Rolling a natural 1 in combat will prevent the attack from hitting it’s target, depending on the circumstances the attack may simply miss, or it may backfire in a more spectacular way.

In order to prevent confusion at the table, always specify a natural 20 rather than just saying 20, if you end up on 20 but only after adding your modifier (for example rolling a 16 on an attack roll and then adding a +4 attack modifier) refer to this as a “dirty 20”.

Out out of combat

Rolling a natural 20 will often guarantee the success of a reasonable attempted action, however it will not always, as DCs can be higher than 20 in some circumstances. you should still point out if you get a natural 20 for the DMs consideration, however you should still add any modifiers (for example if you rolled a natural 20 on a strength check and had a +4 modifier, you should say “natural 20 for a total of 24).

Natural 1s should also be pointed out also including their modifiers (example: natural 1 for a total of 5).

Spellcasting

Spell components

Spell components are largely ignored, especially if the items could have been reasonably acquired and carried throughout the story, for example if you have been anywhere near cotton plants, blankets, pillows, banners, sacks, etc. it would simply be assumed that you had access to any cloth you needed as a spell material component, and you would not need to track it.

More exotic or rare components would be tracked, for example if a spell required you to use a a magical item, or a very expensive gem stone or something along those lines, you would need to actually have it.

Concentration

Spell concentration is not broken by taking damage / getting hit unless the weapon is made of silver, it can only be broken by the following:

  • getting grappled (wisdom saving throw)
  • getting knocked unconscious
  • a spell specifically designed to break concentration

Specific spell alterations:

  • Chromatic orb does not require gem stones in my campaign setting.

Resource tracking

Ammo

non magical or otherwise non-modified ammo is not tracked, if you have a bow and quiver with 20 arrows, it is assumed that you manage to retrieve them from the battlefield during / after combat. If combat reaches a point where you may have actually used all 20 arrows (rare) then I may tell you that your quiver has run dry - however you do not need to track this, I will. the same goes for crossbow bolts, slingshot ammo, etc.

magical or otherwise modified ammo is tracked, and is often consumed on use, for example a magical arrow that does an additional 1d6 frost damage, would either be destroyed, or converted back into a regular arrow after firing it. modified items such as poisoned darts can be collected but in their regular state, for example if you fired a poisoned dart at a creature, you could reclaim it after combat, but it would now be a regular dart.

Misc

Drinking a potion is a bonus action

You may use your bonus action to consume a potion. You are still allowed to spend your main action on consuming a potion, however you may not consume more than 1 potion in 1 turn (no using your bonus action AND action to consume multiple potions).