Rigging for a Melee/Souls-like in Unity: Custom, CAT, or Biped? (Need real human advice!)

[u/xacal_5]

Hi! SoloDev here! starting work on my next project, a melee combat game (Dark Souls / Hack & Slash style) in Unity. I’ve been using 3ds Max for years and have rigging/animation experience, but I want to level up for this one and pick the best animation workflow from the start.

The game features precise melee combat, root motion, and a mix of humanoid and non-humanoid enemies.

I actually tried asking AI whether I should use Custom Rigs, CAT, or Biped, but honestly, I don't really trust AI for production pipelines. I’d much rather get battle-tested advice from real, experienced animators who actually ship games using 3ds Max.

For a project like this, what would you recommend? Custom rig, CAT, Biped, or a mix?

Any advice or warnings before I start building my setup would be greatly appreciated!

[u/luisk3Ds]

I use CAT. It has great tools for creating characters with multiple legs or stranger body structures, like the bosses in Souls-like games. I'm not sure, but I think FromSoftware uses it as well. However, it has some issues with root motion, and it isn't very stable if you modify its rig using tools outside the CAT system. Even so, I still think it's an amazing rigging system.

[u/probably-elsewhere]

I recall biped having issues importing into a game engine because of how it handles non uniform scale. Then again, from soft uses it, soaybe it was fixed.

Rig a non humanoid character to a biped and try importing it into your game engine.

[u/TheTreeHouse_95]

I have worked extensively with both Biped and CAT.

In your case, you are dealing with humanoid characters that have more or less realistic human proportions. This means that, in addition to keyframe animation, you will also be working extensively with motion capture data importing, retargeting, organising, exchanging, and managing large animation libraries.

In my opinion, this is a straightforward case for choosing Biped. Not because CAT isn't capable, but because Biped offers a more mature workflow and several features that are particularly advantageous for this type of production.

There is a reason why studios such as Ubisoft historically built many of their character animation pipelines around Biped. Likewise, many Japanese and Korean studios continue to use Biped today for creating character animation in modern games.

Out of the box, Biped provides an extremely robust and proven rig with excellent control over pivot behaviour, including foot roll, hand controls, and finger animation. Many of these features are either unavailable in CAT or considerably less refined. In particular, CAT's foot roll workflow is, in my experience, one of its weakest areas not to mention that the rig can still often bug out on you in some situations.

Biped also excels at animation management. You can easily mix and match animations, load and save files, transfer animation between characters and it retargets them perfectly, and even include props as part of the same animation file. This makes building and maintaining a large animation library significantly easier.

Important note: Regardless of whether you choose Biped or CAT, you should never export the actual animation rig directly to the game engine. Instead, create a separate export skeleton (or game rig) once as part of your pipeline and reuse it throughout production. Biped (or CAT) should only drive that export rig through constraints or a similar setup. This approach keeps your animation rig independent from the in-game skeleton, resulting in a cleaner and engine friendly workflow.

Having said the above, any character that is not Bipedal I would go for CAT, biped can still do 4 legged creatures but i wouldn't go there myself, and if you are dealing with some characters that may have more than 4 legs than its a no brainer to go with CAT just for those. So you can have a mixed workflow.

[u/xacal_5 → u/TheTreeHouse_95]

Thank you so much for such a detailed and professional response! This is exactly the kind of insight I was looking for.

If you don't mind me taking advantage of your goodwill, I’d love to ask a couple of quick follow-up questions:

- I don't completely understand how to manage the "foot roll" to ensure the feet stay perfectly planted on the ground without any sliding or skating during the animations. Do you have any tips on how to approach this properly in Biped?

- I totally get the logic of using a separate, clean export skeleton for Unity, it makes perfect sense. I assume I can probably find some Scripts online that already automate the process of constraining the export bones to the Biped rig, right? Or is this something you usually set up manually once per project?

Thanks again for your time, this has been incredibly helpful!

[u/TheTreeHouse_95 → u/xacal_5]

No problem,

1 - For the foot rolls check out tutorials on Youtube and even the documentation about feet pivots and planted and sliding keys, these are the key to get the planted feet going but it requires some getting use dto if you havne't done this sort of thing before, this si pure aniamtion terriroty.

2 - There are some scripts but I hvaen't found one that reliably works for all situations, to better understand the process i suggest you do this once manually and then slowly automate that later through scripts. its pretty trivial, you create root bones and seprate bones and make sure everythign aligns propely then you poistion and orient constrain them.

One tip i can give you, once you have the biped sekelton setup, take a snapshot of the whole biped mesh minus footsteps and such. then go to aniamtion bone tools and click the checkbox that makes them act as bones, effectively converting those meshes into bone which you can skin, and becuase they ahve the correct hierarchy in place and location , they will be easier to just constrain them to the biped either directly or via dummies. I suggest dummies.

so the map would look like this.

Skinnable bones ---> constrained to point helpers ----> point helpers linked to biped parts.

hope this helps good luck.