Combat engagements with lots of units on each side can get very long if you use a system where each one gets to do something individually. Sure, you could do it, but at some scale it becomes necessary to abstract things down to a more manageable size in terms of game mechanics.

If you're running a battle between thousands of hobgoblin troops and an army of humans and elves, you really need some other way to represent and resolve the action. Some game systems include mass combat rules intended for such situations, while others simply assume that such large conflicts are not within the scope of the game.

But you can always add some sort of mass combat resolution system to a game that doesn't have one, to allow the players to engage in such actions. There are plenty that could be co-opted, and some designed specifically to bolt onto any other game. Here are some:

• One-Roll Mass Combat - a free bolt-on system for running D&D-style fantasy mass combats.
• Mass Combat Victory Tracker - a pay-what-you-want abstract system for resolving mass combats in any genre.

Transcript

{PIE fighters engage the skim speeders, which veer in different directions across the salt flat, leaving bright red trails of mineral dust behind them}
[SFX]: vreeeeooooowww... {a PIE fighter flies towards the skimmers}
[SFX]: skkrrkkssshhh! {a skimmer veers across the salt flat}
[SFX]: pow! {PIE fighter fires}
[SFX]: boom! boom! boom! {explosions of red mineral dust as PIE fire hits the salt}
[SFX]: boom! boom! boom! {more explosions}
[SFX]: boom! {another one}
[SFX]: skkrrkkssshhh! {another skimmer veers across the salt}
[SFX]: boom! boom! boom! {more explosions}
[SFX]: skkrrkkssshhh! {another skimmer veers across the salt}
[SFX]: boom! boom! boom! {more explosions}
[SFX]: pow! pow! pow! {another PIE fighter fires}
[SFX]: vreeeeooooowww... {that PIE fighter flies towards skimmers}
[SFX]: vreeeeooooowww... vreeeeooooowww... {new panel; PIEs chase a skimmer, firing at it}
[SFX]: boom! {a huge explosion blows more red mineral dust into the sky behind the pursued skimmer}
[SFX]: pow! pow! {one of the PIE fighters fires at the dodging skimmer}
[SFX]: skkrrkkssshhh! {the skimmer weaves desperately to avoid being hit}
[SFX]: vreeeeooooowww... vreeeeooooowww... {new panel; PIEs descend from the sky towards the ground troops’ trenches}
[SFX]: pow! pow! pow! {the PIEs fire at the ground troops}
[SFX]: pow! {a ground trooper fires back from the trench}
[SFX]: boom! {... and hits one of the PIEs!}
[SFX]: pow! {another ground trooper fires at the strafing PIEs}
[SFX]: vreeeeooooowww... {a PIE has turned and is now chasing a skimmer, heading away from the cliff and the fortress blast door}
[SFX]: boom! {another explosion of red mineral dust raised by PIE fire hitting the ground}
[SFX]: pow! pow! {the PIE fires at the skimmer it is chasing}
[SFX]: skkrrkkssshhh! {the skimmer weaves, its starboard outrigger pod scraping the salt as the vehicle banks into a hard right turn}
[SFX]: boom! boom! {more explosions of red mineral dust erupt from the ground behind the fleeing skimmer}
[SFX]: boom! boom! boom! {new panel; a PIE fighter pilot’s cockpit view of the battlefield, showing numerous interweaving red trails left by the skimmers, dotted by red explosions of dust from ground hits by the PIE fighters; we also see the First Order AT-ATs in the distance, still lumbering ponderously towards the frenetic battle between by the rapid and manoeuvrable skimmers and PIEs}
[SFX]: boom! boom! {new panel; more huge plumes of red mineral dust blow skyward from around the ground troops’ trenches as PIE fighters strafe the ground positions}
[SFX]: pow! pow! {a strafing PIE fighter releases more shots at the stationary troops bravely and defiantly defending the trenches}
[SFX]: boom! boom! boom! {more explosions of red dust spray into the sky around the trench; the air is ablaze with the intense vivid hue of the rhodochrosite, but the trench soldiers valiantly stand their ground}
[SFX]: vreeeeooooowww... vreeeeooooowww... vreeeeooooowww... {new panel; three PIE fighters fly in tight formation after a recalcitrant and defiant skimmer which flees before them}
[SFX]: pow! pow! {the PIEs unleash vibrant green plasma death, forming a complementary contrast with the brilliant saturated red of the mineral plumes being raised by the explosions behind the skimmer as their shots miss their mark; the colour juxtaposition is stark and aesthetically striking, assuming you do not have red-green colour vision deficiency}
[SFX]: Kaboom! {another geyser-like spray of red dust erupts dramatically right behind the pursued skimmer, almost engulfing it but not quite as the velocity of the skimmer sees it safely through the explosion zone before any damage can be done, but it looks pretty amazing, let us tell you}
[SFX]: Kaboom! {this is one of the PIE fighter’s green blasts smashing into the salt ground right in front of the poor skimmer, although admittedly that’s a lot better than a direct hit, trust us}
[SFX]: skkrrkkssshhh! {the skimmer planes its way across the salt on its monoski, desperately trying to evade the pursuit of the three PIE fighters hot on its tail. Will it succeed? Only time will tell, because this is the final panel of the comic, and we will be kept in breathless suspense until the next strip appears! Exciting, isn’t it?}
GM: Okay. Roll initiative for the second round of combat.