The latest Halo Infinite beta showed off the upcoming game's multiplayer chops, including some fairly impressive animation. Game animator Dan Lowe, who's currently employed at Santa Monica Studio but has previously worked on games like Star Wars: Squadrons and Far Cry, has explained in a Twitter thread why multiplayer animation in particular is so hard to get right.

Understandably, many of the problems with creating smooth animation in multiplayer games stem from the fact that these games are likely to prioritise responsiveness, competitiveness, and a number of other elements over the quality of the animation.

The recent Halo Infinite test has some pretty solid multiplayer animation, and it reminded me of a topic that I figured was worth some discussion: Why is animation for multiplayer first person shooters, so challenging? [Thread] pic.twitter.com/IqWmIOgn7Z
— Dan Lowe (@danlowlows) October 3, 2021

Some people may not even notice this, but in general character animation in multiplayer FPS games can often feel like the character is sliding around a bit, as if they’re lacking a solid connection with the ground. pic.twitter.com/y76thqa3OM
— Dan Lowe (@danlowlows) October 3, 2021

Characters might also feel like they lack weight/mass when accelerating, decelerating or changing direction. When we see this, it’s not a reflection on the ability of the animation team, it’s a side effect of the constraints of this type of game. There are reasons for this...
— Dan Lowe (@danlowlows) October 3, 2021

In order for gameplay to feel good, Lowe explains, characters have to accelerate, move, and deccelerate much faster than a regular human is capable of doing. When these unnatural movements are experienced in first-person in a single-player game, players don't get to see how their character actually looks while navigating--but in a multiplayer game, all their movements have to be visible to other players.

Animation somehow has to account for this difference. In a code driven animation system, which most MP games are; the animation is essentially locked to a character controller/physics capsule. If the speeds don’t match up you get sliding feet.
— Dan Lowe (@danlowlows) October 3, 2021

So we edit the animation to try and resolve this: Sometimes by scaling the speed of the animation, sometimes by scaling the stride length, but there are limits to how much you can do either of these before things start to look silly. pic.twitter.com/xCYVDTDYNT
— Dan Lowe (@danlowlows) October 3, 2021

Lowe explains that there's also a fair bit of tension between the first-person view that players experience for their own character, and the third-person view that other players are viewed in.

As such, most of the time, first-person animation teams will create separate first-person and third person rigs and animation sets. The player sees the first person model, other players see the third person model. pic.twitter.com/hUQtlBTPGG
— Dan Lowe (@danlowlows) October 3, 2021

The challenge with competitive games is that this disparity can’t create any kind of competitive disadvantage.
— Dan Lowe (@danlowlows) October 3, 2021

The last big issue with multiplayer animation is mostly technical, constrained by the network needed to make sure all players in the game are experiencing the same thing.

The final challenge is replication. In single player games we have the choice to make our character’s movement code driven or animation driven. Code driven generally feels good to play, but can often give that kind of look of the character sliding around like a hockey puck.
— Dan Lowe (@danlowlows) October 3, 2021

Animation driven motion can give more realistic and nuanced movements, and is essential for things like cutscenes, interactions, or really any move where you need detailed character positioning, but it often doesn’t feel as smooth to control.
— Dan Lowe (@danlowlows) October 3, 2021

They’re each good for different things and it’s great to have both options in your toolbox. The problem with multiplayer though, is that animation driven motion is very hard to replicate across a network.
— Dan Lowe (@danlowlows) October 3, 2021

The full thread goes into a lot more detail on all points, but what we should be taking away from Lowe's lesson is that animation is a hard thing to get right in multiplayer games--so we should appreciate when select games do manage to figure it out.

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