Unity DOTS/ECS/Burst mod tutorials and compatibility

[zolantris]

Hello fellow modders and Unity devs 👋

I want to start conversations on DOTS compatibility and modding with DOTS.

Additionally - as the Unity framework becomes more mature it would be good to have a way forward for modding with the new Data Oriented Tech stack (DOTS)

I'm curious if there are already plans to add support for mod frameworks with games using ECS and Burst Compiler.

(also FYI I am new to DOTS but I want to start a conversation about possibilities).

Background

Unity DOTS allows larger or heavier games to run on multiple cores and making many heavier tasks significantly faster with lower level code via job systems and pooling of tasks etc. (read the docs, I way over simplified this).

Most / all of DOTS require a editor/build time compilation of code.

Problems

The whole dots stack requires editor or build level compilations for it to work. Unity team has not exposed a runtime variant of this for modding. (yet)

ECS Problems

• does not have a runtime baker. It would need to be implemented and maintained. This likely already exists in some ECS extension frameworks.
• Rebake and replace pre-baked modified ECS Entities.
• A hook / layer to interact and update ecs entities.
• ecs jobs would have to have a way to be patched and delegate to patches.
• burst references that are patched must also update etc reference pointing to the old burst binary.

Burst Problems

• bursted code is not accessible by harmony due to it being lower level.
• rewriting bursted code references would need to re-run burst during build step.
  • limitation: burst must be run in the Unity editor.
• Runtime burst generation would have to be created or exposed. It does not exist.
• burst references would have to be updated when harmony patches a bursted method. (I think)

Outcomes

Game Devs

• will have a clear way to create a dots compatible game for modders.
• code changes should align with best practices for DOTS/ECS/BURST.
• Integrating this capability should be painless...taking only a couple days.

Mod Devs

• will have a clear way to override dots games without breaking functionality.

Mod Users

• games continue to work with DOTS and patches do not regress performance
• startup time is not above acceptable value for dots ecs/Burst patches. (maybe 30 seconds).
• Base game systems are not degraded by dots patches. If anything they should be improved.

Inspirations

• https://github.com/Dreaming381/Latios-Framework

[pardeike]

I think DOTS changes the situation a bit. Here are some random thoughts:

– ECS baking is editor‑only and wapping compiled EntityScenes at runtime is non‑trivial

– Burst turns hot paths into native stubs that Harmony can no longer intercept

I rather see a mod SDK that compiles mods ahead‑of‑time (managed + Burst DLL) and a lightweight loader in-game.

I don’t see "plug Harmony in and go" work in a couple of days, the tooling required is non-trivial. Most gains will come from data‑driven extension points rather than IL patching.