D&D 3E/3.5 Why do AoO's exist? Would it wreck 3.5 if I removed them from my game?

[Delta]

In general, combat felt less "real". People could run between two ogres with 5' space between them, fighters could always get a flank for an extra +2 to hit, there was almost no way to prevent rogues from flanking.

Well, what I was about to say to the OP is that you have to go back to 1E/2E rules where the things that provoke AOO are simply prohibited. If you get one space away from an enemy, you are required to stop. If you get hit casting a spell, it is automatically lost. If you are a bowman in contact with an enemy, you cannot fire. Stuff like that.

 

[Bladesong]

I have replaced them with opposing rolls. So if someone wants to drink a potion while in melee, they make a concentration check opposed by the BAB (+10 I believe) of the enemies next to them, etc. If they fail, they do not complete the action. Makes more sense if you cannot drink while being "bumped" around than giving someone additional actions in a round. It works great with everything that has been tried so far: spell casting, tumbling, downing potions, etc..

 

[BASHMAN]

I think the best way to go about this is to say that AOOS incurred by MOVEMENT no longer exist. This will make people take a lot less time to take their turns.

Feats like Combat Casting then would still be useful, etc.

 

[jensun]

Feats like Combat Casting then would still be useful, etc.

I think you are stretching the definition of the word useful quite a lot to include Combat Casting...

 

[mvincent]

I feel that limiting movement around the battlefield (via AoO's) tends to make the game less interesting rather than more. In action movies, the participants in a combat typically move all over the scenery. In D&D however, participants tend to just move straight towards their opponent... and that's it. So many battles seem to be resolved 'at the door', rather than in the middle of some wonderful, interesting room that the DM created.

Also, AoO's tend to slow down and/or complicate play. Noobs certainly have a hard time with them. Were I not such a rules purist, I would've eliminated them myself.

Some other notes (also mentioned here):
Removing AoO's reduces the utility of concentration, tumbling and reach weapons. However, these tended to be overly-useful anyway. It also makes ranged weapons marginally easier (mostly: they don't need to take a 5' step now), but archers weren't overly powerful anyways.

The biggest impact is on big (i.e. large+) monsters. Eliminating their reach advantage can make them easier.

 

[KarinsDad]

As to why AoOs exist in the game, there are two reasons:

1) So that the squad of Assassins cannot just waltz past the King's Guards with the guards having no opportunity to stop them (shy of readying an action). The game is played with a circular initiative system which segments actions apart from each other.

2) For balance reasons against flanking Rogues, casting spellcasters, and missile users. Unfortunately, WotC put the AoO balance rules in and then made it extremely easy for all of these types of characters to avoid the AoO anyway.

 

[RigaMortus2]

I think the Star Wars RPG does not have AoOs in their system.

 

[frankthedm]

I feel that limiting movement around the battlefield (via AoO's) tends to make the game less interesting rather than more. In action movies, the participants in a combat typically move all over the scenery. In D&D however, participants tend to just move straight towards their opponent... and that's it. So many battles seem to be resolved 'at the door', rather than in the middle of some wonderful, interesting room that the DM created.

If someone it too afraid to draw an AoO for a much better combat position, screw them. PC moves by guard and takes his AoO, PC keeps going. Rest of the PCs funnel by the guard who used up his AoO. Heaven forbid a PC be attacked by someone who was going to take a swing on him anyhow.

 

[Grog]

AoOs make the game almost impossible to play without miniatures. If you take them out, I think you could run a game without minis pretty easily.

 

[IcyCool]

Can your game survive without AoOs? You betcha. It will work pretty well in fact.

But the poor little wizard behind your front-line fighters will be SOL when the burly Orc walks around the Fighter and pounds him into mage-paste. So it will likely affect your players tactics.