If you're looking for a faster, more abstract, more…interesting…way to deal with 4e combat, you might want to look at it as a skill challenge.
The Attack Skill
Lets start from the ground up: your attack rolls work like skills: roll a d20, add your attack bonuses, and compare them against your enemy's defense. This mechanic is identical to a d20 skill roll against a DC, all that changes is the things you're adding. Your attack roll gets an added portion, to it, too: you roll for your damage.
To make this work as a skill challenge, we get rid of that bit: in this situation, you don't roll for damage.
Instead, the result of your attack roll means that you have successfully damaged your target. The quantity of damage doesn't matter much. By default, opponents who have been damaged 6 times are knocked unconscious. Opponents who have been damaged 3 times are bloodied. You can represent this visually with "hit boxes":
$000 | 000$
Each time the monster takes a hit, you check off one box:
$X00 | 000$
When half the boxes are checked, the creature is bloodied:
$XXX | 000$
By default, this essentially means that each character must hit six times in order to beat the challenge. In skill challenge terms, each character requires 6 successes, for a total of 30 successes for a typical 5-person party. Easy, no?
Not every hit is always the same in a combat, of course. Powers deal damage on a miss, auras deal continuous damage, monsters have resistances, etc. That's handled like this:
- Low Damage: When dealing "half damage," or when dealing static damage that isn't rolled (such as with magic missile, or cleave or an aura), you can perform a "soft hit." Instead of checking off the entire box, you just check off half of it (instead of an X, you put a /; two /'s = 1 X).
- Crit: Critical hits deal +1 hit.
- Resistances and Vulnerability: These negate 1 hit of the appropriate resistance, or add +1 hit of the appropriate vulnerability. A creature with cold resistance, for instance, takes -1 hit from cold-based attacks. A creature with fire vulnerability takes +1 hit from fire-based attacks.
- Insubstantial: This turns every hit into a "soft hit" as above.
- Regeneration: This restores 1 hit every round.
Of course, you have an active opposition in combat. Enemies are trying to kill you just as you are trying to kill them. Each time an enemy's turn comes up, they roll an attack against your defenses, and, if they hit, you are damaged. A character can likewise be damaged 6 times before they are bloodied, and 3 times before they are knocked unconscious. When a character spends a healing surge, they "repair" one hit.
- Brutes and Soldiers can be damaged 4 times before they are bloodied, and 8 times before they are knocked unconscious.
- Lurkers and Artillery can only be damaged 2 times before being bloodied, and 4 times before being knocked unconscious.
- Defenders can be damaged 4 times before they are bloodied, and 8 times before they are knocked unconscious.
- Strikers and Controllers can only be damaged 2 times before being bloodied, and 4 times before being knocked unconscious.
- Strikers, using a melee or ranged attack, deal +1 hit with each successful attack.
- Controllers, using an area or close attack, can roll two attacks against two different targets, each hit dealing 1 hit.
- Area and Close attacks can hit a group of monsters: 2 creatures at once. These normally take a -2 to the attack rolls, except for Controllers.
- Encounter powers deal enough damage to deal 2 hits to one creature, or 1 hit each to 2 creatures.
- Daily powers deal enough damage to deal 3 hits to one creature, or 1 hit each to 3 creatures.
- Note that Strikers add +1 hit to their Encounter and Daily powers as well, as long as those powers are Ranged or Melee attacks.
Because skill challenges are more abstract, range can be abstract as well. A character can move into or out of melee with a move action. When in melee the character provokes attacks of opportunity for moving, and for using ranged or area attacks. Attacks that are melee attacks or close attacks can hit other melee-ranged creatures.
When out of melee, a character does not provoke opportunity attacks for any action. They can only hit creatures with area or ranged attacks.
When subject to a forced movement effect, a pull causes a creature to come "into melee," while a push moves them "out of melee". A slide can move them either into or out of melee.
To gain flanking, you need to spend a move action (and provoke attacks) while you are "in melee" with at least one ally and one enemy.
Using This For Other Task Types
This works solidly for combat, but it adds some grist to the mill for other task types as well: Interaction, Exploration, and Discovery could all use a similar system, where each character has their own "success meter" measuring how many successes (hits) they've achieved (out of six each). This opens up some space for powers that can affect the scores in different ways, like with the Striker and Controller mechanics, or that open up the player's own resources, like the Defender mechanic. This means that other task types should be "aggressive:" rather than punishing the group for failures, the "challenges" try to work against the party. A Discovery task, for instance, might require you to find out the mystery before something happened (like the opportunity was lost, or the plan went into action).
This essentially creates a sort of "lite hit points," simply described in terms of successes.
Adding Back In Damage
Let's face it, damage is fun to roll. This system doesn't include damage, but it certainly could.
You could simply treat a damage dice as an additional step, rolling for them. If the damage exceeds a certain threshold, then it is a "hard hit." If it does not, it is a "soft hit." You can also add on "additional hits" for multiples of that threshold.
By default in 4e, the threshold is $Level +3$. This is also a good median to use, if the average damage is 1d8+level.
What We Have Learned
This concept translates D&D combat as it exists into a more abstract realm — closer to the realm occupied by skill challenges. This is pretty close to how OD&D actually worked — before Gygax invented the hit point, hits were tracked very abstractly. This also gives combat and skill checks more of a "shared language." We can talk about a "success" meaning something similar in combat and in a skill challenge.
It has some flaws, though. Rolling damage is fun, and this removes that step, leaving those weirdly shaped dice out in the cold. Certain powers are probably special corner cases, to boot. It might be a little *too* abstract for many groups, though: a hit is a hit is a hit, without much distinction (though there is a mechanic for "big hits" and "little hits").
So, ultimately, it shares some of the flaws of skill challenges: roll, roll, roll, with some flavor, is a lot like playing a basic 1e Fighter: the same thing, every round. It also keeps a dilemma we find in the original 4e skill challenge mechanic: combat has many more interesting things to do than noncombat does.