Combat House Rules Mashup!

Fun fact: This post will definitely change from time to time.

I've held back from introducing extra rules to combat for a long time. After 4e I wanted to downplay combat and keep it simple, quick and deadly.
But combat is always going to be interesting and so the rules creep in. On the philosophy of combat rules, other people have already said it better.

So how do I do combat? By mashing other people's stuff together of course!
A meaty base of LotFP's combat actions and low magic philosophy.
A splash of Hack & Slash's death crit table.
A pinch of Trollsmyth's Shields Shall Be Splintered.
A twist of dual wielding from whoever came up with that one. (Scrap maybe?)
A big ol' pound on the sauce bottle of Last Gasp's weapon types, reach, called shots, and Notches.
A scoop of Brush of Fumbling's weapon quality.   
And finally, a lightly spiced garnish of my own tables.

I like to have rule summaries that fit neatly on A4 pages, my games tend to have new players kicking around so it's good to have something they can read in their own time. There is no experience worse than having a lot of people talking to you and each other when you've never played this before and don't want to embarrass yourself. 
My combat handout is here if you're into that sort of thing.

Main Things

HP
HP for the PCs is all their luck, skill and fatigue. Lose it all and you start taking Death Crits. This is the same as the super awesome Hack & Slash table except that Pain total is also the number you have to roll over on your hit die every round to stay conscious. Con mod applies.

Initiative
Simple initiative because I've never seen a situation where individual initiative is more useful than annoying. Ties are broken by the side with the guy with the highest dex or else in favour of the PCs.

Crits and Fumbles
On a natural 20 to hit, roll again to confirm.
1: Whoops, just roll normal damage.
2-10: Max damage
11-19: Roll d100 on the Overcrit table!
20: Roll twice on the Overcrit table!

On a natural 1 to hit, roll again to confirm. 
20: Nice recovery! Roll to hit again. 
11-19: You simply miss
2-10: roll d100 on the Critical Fail table!
1: roll twice on the Critical Fail table!

Fighters add their level to confirm rolls because they are well trained and fighty.

Weapon Funkiness
Different weapons are good for different things. I stole Logan's table and renamed things slightly so that players can choose what modifier is closest to the weapon they want. I also went and stole the thing where the armour types are changed to Light, Medium and Heavy so the players can make up what it looks like.
Weapons with more than one type of modifier and/or do extra things are less common and cool to have! They'll be good in treasure instead of generic magic items.

• Stabby: Swords, spears. If you haven’t been hit this round roll twice for damage, take the best.
• Smashy: Hammers, clubs. When you attack choose +1 vs Medium or better, or smash at armour joints with an attack which reduces Heavy AC by 1 but deals half damage.
• Choppy: Axes, halberds. Minimum half damage vs. Light or less.
• Flaily: Flails and flail accessories. +1 vs Medium or better, ignores shield AC bonus. You can choose to attack their weapon, no damage but pass a Strength check to disarm on hit. On any miss roll under your AC or hit yourself you goof.
• Shanky: Daggers, stakes. If you hit someone you can grab hold and keep stabbing. You automatically overcrit on each round you win a wrestling roll. Anyone with a Medium or larger weapon has to kick you away before they can attack you with it.

 

Giant flesh golems are nature's munchkins

Reach

Logan also managed to make dex mods apply to combat without having to bog the game down with individual initiative. The man's a genius!

When wielding a Medium or larger weapon you can make a contested initiative roll to attack first when someone with a Minor weapon closes into melee range.
When wielding a polearm you can make a contested initiative roll to attack first when someone with a smaller weapon closes into melee range.

Shield Break!

Shields Shall Be Splintered because it's got the best simplicity-to-impact ratio of any house rule I've ever seen or used. So elegant.

Dual Wielding

Roll to hit with your dex, roll damage for both and pick the highest. Doubles means that you add them together! Only one type of funkiness applies, declare before rolling. 

I like these rules together (Reach, Shield Break, Dual Wield) because it means that there's a nice balance between weapon combinations. 
Two handed weapons have bigger damage dice and have an advantage over people with smaller weapons.
A Shield gives superior defensive abilities and goes great with Stabby weapons.
Dual wielding focuses on consistent damage and favours pairing weapons with lower damage ranges for more likely doubles.

Called Shots
Roll to attack twice. If both hit, it happens. If one hits, it doesn't. If both miss, you fail in an ironic manner and something happens to you like missing your next turn or falling over.

I was using some shithead's crit-range-extension thing for a while, but I think I like this better. I put this first on the list of Fancy Stuff people can do in combat because it's the most important one

Wear and Tear
I want to see people emerging from the dungeon wearing raggedy armour and holding hastily macgyvered weaponry because I am mean. I also love the idea of players being stoked to find a well made but otherwise mundane sword halfway into a dungeon crawl.
These rules are a result of the joyous union between Last Gasp and Brush of Fumbling.

Weapons have a Quality rating between 5 (shoddy, improvised) and 1 (masterwork). Higher quality means higher prices and vice versa.

Every time you roll under your weapon's Quality to hit in combat your weapon takes a Notch.
If you ever roll under the number of Notches for damage it breaks.

Armour gets Notched if you're hit on a 19 or 20, each Notch reducing its AC by 1. If this would make it worse than wearing nothing at all you can choose to have it fall to pieces instead. 
Keep it to fix later or destroy it now before the gunkbear attacks again? You decide!

Repairs cost 10% of item cost per Notch.
A dwarf with simple tools can spend a day to repair one Notch.

I just realised that using two weapons with different qualities could cause issues! If you're dual wielding and roll under one weapon's Quality but not the other, only that weapon gets a Notch. If you roll under both then both weapons get a Notch. 

Bring more daggers next time, kid.

Maintenance -

For every hour you spend cleaning and oiling your stuff you get a “free” Notch. If any of your weapons or armour gets Notched you can use up one of these instead.

There's an arbitrary limit of three at a time, but they decay at one a day if they're not used.

I like this because it means fighters have something to do in the morning while they're waiting around for the wizard to memorise his spells, and the decay-over-time thing means there's an advantage to a daily maintenance regimen. 

Armour could also get Notched by particularly harsh conditions or long travel, well maintained gear avoids that problem.

It also means that it's probably too much effort for a wizard to bother with armour which is nice and thematic!