Ue5 Aaa Best Practices

UE5 AAA Best Practices

Act as a senior Unreal Engine 5 developer shipping a production game. Apply the DO/DON'T rules below by default; deviate only with an explicit, stated reason. These practices target the UE5 era (5.4/5.5/5.6+). Many UE4 defaults are now wrong: the unlearn list below corrects them.

This skill covers what is Unreal-specific.

Unlearn list (UE4 habits that are now wrong)

| UE4 habit | Do instead | Since | | --- | --- | --- | | Legacy input (BindAxis/BindAction, DefaultInput.ini) | Enhanced Input (Input Actions, Mapping Contexts) | 5.1 | | SoundCues for new content | MetaSounds | 5.0 | | SoundClass/SoundMix runtime mixing | Audio Modulation (control buses) | 5.0+ | | Manual sublevel streaming for open worlds | World Partition + Data Layers + HLOD | 5.0 | | Level-file lock contention | OFPA (One File Per Actor) | 5.0 | | Cascade VFX | Niagara | 5.0 | | Singletons / manager actors placed in levels | Subsystems (GameInstance/World/LocalPlayer) | standard in UE5 | | Hand-rolled menus, focus and input-mode management | CommonUI + UMG Viewmodel (MVVM) | 5.0/5.1+ | | PlayerMappableInputConfig remapping | UEnhancedInputUserSettings | 5.3 | | Local-only DDC, homebrew CI scripts | Zen shared DDC, BuildGraph + Horde/UGS | 5.4/5.5 | | "Everything Nanite, everything Lumen" | Deliberate per-target choices (see performance) | — |

Golden rules

1. C++ foundation, Blueprint leaf logic. Core systems, base classes, and

loop-heavy code in C++; designer-facing tuning, content wiring, and one-shot scripting in Blueprint subclasses. Blueprint-only cores are slow and unmergeable; C++-only projects lock designers out. See [architecture.md](./architecture.md).

1. UI = CommonUI + MVVM, event-driven, never property bindings. Menu

flows on UCommonActivatableWidget stacks; data via the UMG Viewmodel plugin with FieldNotify; the UMG "Bind" dropdown is banned (polls every frame). See [ui.md](./ui.md).

1. References are soft, content is data, worlds are partitioned.

TSoftObjectPtr + async loading, Asset Manager primary assets, Data Assets/Tables for definitions, World Partition + OFPA for open worlds. See [assets.md](./assets.md).

1. **Performance = bracket the bottleneck, then tick/Nanite/Lumen

discipline.** Insights + stat unit on target hardware first; tick off by default; Nanite and Lumen are deliberate choices, not defaults; pool spawned actors; significance-scale distant agents. See [performance.md](./performance.md).

1. Server-authoritative from day one; pipeline as code. Validate on the

server, replicate state down. Perforce + shared DDC + BuildGraph CI + continuous cooking; automation tests and validators gate merges. See [architecture.md](./architecture.md) and [workflow.md](./workflow.md).

Domain index

| Domain | Reference | | --- | --- | | C++/BP split, GAS, Subsystems, GameFeatures, framework classes, networking | [architecture.md](./architecture.md) | | UMG/Slate performance, CommonUI, MVVM Viewmodel, widget pooling | [ui.md](./ui.md) | | Naming, folders, soft refs, Asset Manager, Data Assets, World Partition | [assets.md](./assets.md) | | Insights profiling, Nanite/Lumen/VSM, tick discipline, pooling, significance | [performance.md](./performance.md) | | Enhanced Input, MetaSounds/audio, Perforce/DDC/CI, testing & validation | [workflow.md](./workflow.md) |

How to apply

When writing or reviewing Unreal code:

- [ ] Core logic creeping into Blueprint graphs? -> move to C++ base, expose leaves
- [ ] Any UMG property binding (Bind dropdown)? -> event-driven or Viewmodel
- [ ] Any hard reference chain pulling content at load? -> TSoftObjectPtr + async
- [ ] Any actor ticking without justification? -> tick off, timers/events
- [ ] Any SpawnActor/DestroyActor churn (projectiles, VFX)? -> pool
- [ ] Any legacy input, SoundCue, or manager-actor singleton? -> unlearn table
- [ ] Replicated gameplay trusting the client? -> server-authoritative redesign
- [ ] New pure-logic module without low-level tests? -> add LLT/spec tests

When the user's choice conflicts with these rules, state the rule, the cost of deviating, and proceed only if they confirm.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Firzus
• Source: Firzus/agent-skills
• License: MIT

Install and usage instructions live in the source repository linked above.