So, this is a technique I use where the PCs are commanding troops in battle. It assumes the PCs are reasonably strong, so that a single mook is not much threat to them: I've used it both for high level OSR games (IE once they hit level 9 and get their castle) and in the Wraith game I run for when they're at war with Specters.
The basic thinking is this: Rolling out each round of combat will get really tedious really fast, so don't do that. Assume that the PCs are able to make a difference where they focus their efforts, but can't be everywhere at once.
The method I use is to divide the scene into 'frames', each frame being a snapshot of the battlefield as the situation develops.
Each frame presents the general situation of the battlefield, and the results of the PCs actions in the previous frame. It then lists a number of points where the PCs might want to intervene.
Here's an example from tonight's (text-based) Wraith game, in which wax-themed spectres were besieging the city of Barcelona:
FRAME 3 RESULTS: Ember, you're able to cut down the wraiths hauling the bell, and then turn your attention on the bell itself - you attempt to cleave it in twain with your blade, but only succeed in striking it and producing a mighty GLONG! that causes the very walls to shudder and both wraiths and spectres to drop to the floor clutching their ears. Sophia, the waxy priests shriek and burn, and their torrent of angst ceases as Moire and her pet squid-monster smash into them from the flank, totally destroying the formation. Sun-Come-Dance, fucking EVERYTHING IS ON FIRE - this is a problem for the spectres pursuing you, the survivors you're with and yourself, but for now you're outrunning the flames. The spectre's seige engines remain pinned down by the hierarchy's firepower.
FRAME 4: More spectres swarm over the breaches in the walls and into the city, running amock and cutting down civilians and wounded legionaries where they catch them. Waxen knights climb the walls, hoping to secure the beach-heads their more expendable cousins have made. The approaching collumns of spectral reinforcements are held at bay by all of Sun-come-dance's fire, at least for now. Out of the wax moat, crude hulking wax giants emerge, lumbering towards the walls. A cadre of spectral engineers scurry from cover to cover towards the now-damaged seige-engines, attempting to repair them and bring them to bear. Following the giant squid-spectre, a small warband of creatures resembling a cross between toads and sea anemones crash gibbering and shrieking into the wax-army's flank, and a densely-packed melee breaks out. Lord Soot, Ember's second-in-command, is cut down by a wax knight and falls from the walls, bleeding plasm.
Here, I'm responding to the player's previous actions first. Ember dealing with what is basically a Skaven Screaming Bell used by the specters, Sophia attacking spectral priests, Moire allying with fish-monsters to attack a vulnerable flank, and Sun-Come-Dance* leading scattered wraiths behind the enemy lines to do arson.
The I introduce potential problems. Most notably, the breach had been ignored for two frames already, so now it's going to mean horrible defeat if not dealt with. Other elements pose threats, attack the PCs assets, or add complications. For example, not dealing with the siege engines getting repaired will mean the specters are able to start a full bombardment, resulting in heavy casualties on the wall's defenders.
(*One of my players asked if she could play the ghost of a dead neanderthal. it's like they know my tastes or something)
Each frame, the PCs get to do one thing that responds to one element of the frame. If an element goes ignored (like the breach here), then the enemy succeeds and the situation gets worse. If they choose to deal with a problem (by a method that makes sense) then that problem goes away. Where there's doubt, a simple roll might be needed. In OSR, this is probably 'roll d20 and hope its under a stat', in WoD it's normally 'Int + Strategy' or some such.
If the PCs command their minions to do something, then that uses their action for the frame, and the minions will keep doing it (or things like it) until given new orders. So a PC can throw orders out each frame to bring more and more minions to bear.
Once you've seen what the players are doing, work out how they succeed, what happens to the threats they ignore, and narrate the results.
It's pretty simple.
The key thing here is to do four things:
- Minimise the use of game mechanics and focus instead on the PCs as directing the flow of a large battle that's handled through narration.
- Divide the battle into distinct snapshots where the PCs are presented with many problems to fix: more than they can fix in one go.
- Punish them for the problems they don't fix, reward them for the problems they do.
- Keep introducing new factors and moving the dynamics of the battle forward.
Eventually either the PCs bring enough forces to bear that they have an obvious advantage, and you can call the battle as a win for them, or else they ignore a problem for long enough that it becomes unstoppable, and you can call a loss.
So yeah. That's how I do battles in my games. My players seem to have fun with it.