DnD is probably the most played RPG brand for me , although I have played many RPGs over the years.
I pretty much skipped version 3, 3.5 and 4, but I played a lot of ADnD 1st and 2nd ed, Pathfinder (cleaned up 3.5) and now 5th edition.

Over the many years (since the earlyish 80s I suppose) I played DnD, I've seen a lot of odd and interesting houserules.
Generally house rules are there to address perceived issues with DnD rules or promote a certain flavour or style of DnD..

I'm curious as to what odd houserules you have come across and your perception of them are.

An interesting one I came across in ADnD was the desire to be able to "Knock out" an opponent, so regardless of having buckets of HPs, you could still knock someone out with non-lethal damage.
An approach to this I remember years ago in ADnD was this if you have the drop on someone (they're not aware of you, complete surprise)  AND they DON'T have a helmet, the opponent's HPs are only equal to their 1st level HPs.
So when you're specifically trying to knock them out, you do your damage as usual, but it's only stunning, so you won't kill them.
However there's potentially a LOT less HP damage to do to them and you get to knock them out.
Some of the justification for this was that true HPs are only at 1st level which are a reflection of your initial training and Constitution. All the higher level HPs are your ability to minimise and absorb  damage.

A variant on this was to use the pure CONSTITUTION stat, not rolled HPs + CON bonus.

An interesting approach, although I think WAAAYY powerful, especially for Rogues..  But then again, for a certain style (a DnD Lankhmar campaign?)  could be a lot of fun.

Like most folks, I have a few I use regularly. Here's one I devised a couple of years ago when 5E came out, and it seems to get good reviews from other people:  The 0-level funnel (a DCC idea) for D&D characters. Roll up your character by determining attributes and selecting a background. Begin play with 1d6+con bonus HP and whatever benefits you have from your background. Play until you complete 1 significant session or get 100 EXP (whichever comes first), at which point you select a class and become 1st level in that class. Re-determine your HP by rolling 1 HD for your new class (+con bonus if appropriate), and keep the higher of your 0-level HP or your new roll. It's pretty simple, really, but leads to tons of crazy fun. Players really enjoy developing a character that has some sort of connection to real life and then just letting loose. People do different things when they don't start play with a class-defined 'role'.

Quote from: Larsdangly;1003588Like most folks, I have a few I use regularly. Here's one I devised a couple of years ago when 5E came out, and it seems to get good reviews from other people:  The 0-level funnel (a DCC idea) for D&D characters. Roll up your character by determining attributes and selecting a background. Begin play with 1d6+con bonus HP and whatever benefits you have from your background. Play until you complete 1 significant session or get 100 EXP (whichever comes first), at which point you select a class and become 1st level in that class. Re-determine your HP by rolling 1 HD for your new class (+con bonus if appropriate), and keep the higher of your 0-level HP or your new roll. It's pretty simple, really, but leads to tons of crazy fun. Players really enjoy developing a character that has some sort of connection to real life and then just letting loose. People do different things when they don't start play with a class-defined 'role'.

Oh yes, I remember buying an official "Module" for ADnD which used an approach like this.

You start as a zero level character and are expected to "Roleplay" what class you want to be.
Characters start with something like a D6 HPs and casters are expected to kind of act like the caster class, such as use the various scrolls around the adventure and I believe a spellbook was available to use as well at some stage.

[edit]
Here's the scenario in question:
https://en.wikipedia.org/wiki/Treasure_Hunt_(module)

 
It was a lot of fun actually and the players really enjoyed it.

I also liked the AD&D 2e versions with KOs d% values. You see those values in the Punching & Wrestling Table. And they have a weapon variant in IIRC CH:Fighter or CH:Thief. There was a weapon size/dmg limit, IIRC, and basically was each point of dealt weapon damage × 5% = d% KO chance. I think it must've been CH:Thief because I remember it also worked with Saps at 10% per damage point. It was pretty awesome!

Had a thief sneak up on another thief and fighter pair. He got the drop and decided a dagger handle strike to sap the fighter (exceedingly risky). He rolled max dagger damage, and I rolled under the fighter's 20% KO. That changed the battle completely. He then took out the other thief, which was neck and neck, as it was between 1st lvls. Total luck took a hit n run surprise into a victory. Good times, good times.

If you want to check out my 'house rules', you'll need to wait a couple of weeks, for the release of Lion & Dragon.