1. This isn't as much a house rule as it is a variant in the DMG, but it's good to know up front that we play this way. There are no skill proficiencies ("Perception" etc). Instead, you choose two of your six abilities, for example Dex and Wis, and are proficient with all ability checks (such as foraging for food or grappling) with those two abilities. This is only for ability checks, and not for tools, saving throws, attacks etc, which all work as normal.

Be aware that Constitution and Charisma are not going to be rolled very often. Instead, if you want your character to say something, say it. If you want your character to look in a drawer, say that you look in a drawer. (There is one very specific situation where charisma checks are being made and that's during the downtime rules. "I spend a week in this town trying to make friends" "OK, one week later…". Maybe future house rules will add more opportunities for these checks.)

1. Something you might want to have in mind when choosing spells:

Spells that targets an area of effect instead target a fixed number of enemies. For example, Burning Hands hits two enemies. (This is is less of an house rule and more of an optional rule from the DMG, I think it's page 249.)

Some spells, notably Light, Dancing Lights, and Goodberry, are now more expensive to use.

1. A kind of weird take on hit points: Oh, Injury!

There's also some other things but they don't really matter for character generation:

1. Introducing Late Night Fighting
   
2. Defense rolls i.e. you'll roll to defend instead of enemies rolling vs your AC.
   
3. I don't like using a lot of maps&minis. You're standing in a room, not looking down on a room. But, I don't want to make that punishing for you either; if you want to say "we go to the room where we saw that bull statue", for example, that's fine. It's not about making you get lost in the dungeon. That's what we have the wilderness for.
   
4. More uses for inspiration, and more ways to get it.
   
5. The rules and consequences for climbing have been clarified. Thanks to Veins of the Earth. The thief's class ability "second story work" has been expanded.
   
6. The assassin's class ability to infiltrate in disguise has been clarified and buffed slightly.
   
7. Probably more things that I forget now. I'm an idiosyncratic DM :/

Generally if you want to do things we'll find rules for it or make up rules for it. Sometimes very difficult and hopeless rules.

Also optional rules from the books that we use:

• Targets in areas of effect (as listed above under spells)
• Cleaving (i.e. if you one-shot an undamaged enemy with a weapon attack, your damage can carry over to another enemy) from the DMG
• Eliding skills (as listed above under skills) is also something that the DMG suggests
• The defense roll thing is from UA so it's not completely new either, I just fixed the math
• Feats & multiclassing
• The detailed encumbrance rules from PHB p176, but with house ruled item slots of different sizes rather than pound weight.

and don't use:

• Point buy for stats. Instead, use standard array or roll 4d6-drop-the-lowest-arrange-in-any-order. PS have a witness if you choose to roll your stats, it's gonna be epic if you start racking up a bunch of eighteens.
• Flanking (the DMG optional rule, that is — the rogue still get their normal Sneak Attack) and a bunch of other stuff.