MegaLights in Unreal Engine 5.8: how hundreds of shadowed lights work

MegaLights is the part of Unreal Engine 5 that lets a scene have hundreds of moving, shadow-casting lights without the frame rate falling with each one you add. Instead of computing every light for every pixel, it traces a fixed number of rays per pixel towards the lights that matter most and cleans the result with a denoiser, so its cost stays roughly constant. It was experimental in UE 5.5, beta in 5.7 and became production-ready in UE 5.8, released on 23 June 2026. It expects current-generation consoles or a ray-tracing-capable PC, and it is not Lumen: MegaLights does direct light, Lumen does the light that bounces.

This explainer follows Epic’s UE 5.8 documentation and release notes, read on 14 October 2026, and ends with what the COLONIZED development build does with it, which is nothing yet.

The problem it solves

In a classic deferred renderer, every light that can cast shadows costs a shadow pass and a lighting pass over the pixels it touches. Ten lights are fine. A corridor with sixty emergency lamps, a hangar full of floodlights or a street of neon signs is not: the cost grows with the number of lights and their overlap, so artists end up switching shadows off, faking lights with emissive materials or shrinking their radius until the scene looks flat.

MegaLights changes the question. Epic describes it as “a stochastic direct lighting technique, which solves direct lighting through importance sampling of lights”. For each pixel it picks a fixed number of samples among the lights that affect it, weighted by how much each one is likely to contribute, traces rays to check visibility, and lets a denoiser rebuild a smooth image from those samples over space and time.

What that buys, and what it costs

	Classic shadowed lights	MegaLights
Cost as lights are added	Grows with the number of lights and their overlap	Roughly constant: a fixed number of rays per pixel
Shadows	A shadow map or ray-traced shadow per light	Ray-traced per sample by default; Virtual Shadow Maps optional
Light shapes	Area lights are expensive	Built for area lights
Weak point	Many lights	Pixels lit by many strong, overlapping lights get noisier
Hardware	Any	Current consoles and ray-tracing-capable PCs

The trade-off is honest: when the lighting at one pixel gets very complex, MegaLights does not get slower, it gets noisier. That is why Epic’s advice is about helping the sampler choose well.

From experiment to production

Version	Release	Status of MegaLights
UE 5.5	November 2024	Experimental
UE 5.7	November 2025	Beta
UE 5.8	23 June 2026	Production-ready

According to the 5.8 release notes, the team “greatly reduced noise” and improved performance to reach 60 fps. Version 5.8 also added support for subsurface transmission, translucency lit through a froxel grid, higher-quality lighting on the front layer of translucent surfaces, IES profiles on volumetrics and translucency, lighting channels, cloud shadows and first-person weapons, plus debug views: a light finder, a ray visualiser and views of shadow casters.

What it supports

• Local lights: once MegaLights is on, it handles every local light, and you can switch it off light by light.
• Directional lights: disabled by default; you can enable them manually.
• Particle lights: only when Niagara spawns them.
• Light functions: when they are compatible with the Light Function Atlas and the atlas is enabled.
• Shadows: per light, ray tracing (the default and recommended method) or Virtual Shadow Maps, which only approximate area shadows and add memory, CPU and GPU cost for each light, so Epic says to use them sparingly.

What it needs, and where it does not run

MegaLights is designed for current-generation consoles and PCs that can do ray tracing. When you enable it, the editor asks you to turn on hardware ray tracing support, which Epic recommends. It does not support mobile, Switch or previous-generation consoles, and it does not work with the forward renderer.

It also leaves some things out: per the documentation, water, clouds, heterogeneous volumes and local volumetrics are not supported, and ray-traced alpha masking needs an extra console variable with a noticeable cost.

How to switch it on

1. Enable it in Project Settings → Rendering → Direct Lighting.
2. Accept hardware ray tracing support when prompted.
3. To exclude a scalability level or device profile, set r.MegaLights.Allow 0 there.
4. Leave strong directional lights, like the sun, out of it: most projects light the sun with deferred lighting and Virtual Shadow Maps and use MegaLights for local lights.

Epic’s tuning advice is short: do not place lights inside geometry, keep their bounds tight, narrow the attenuation ranges, use spotlight cones and barn doors to limit what each light reaches, and merge clusters of small lights into one area light. All of it helps the sampler spend its rays where they count.

MegaLights and Lumen are different jobs

MegaLights computes direct light: the light that travels from a source to a surface. Lumen computes indirect light and reflections: what bounces off walls, sand or a hull and fills the shadows. They are complementary. A scene can use Lumen for global illumination and MegaLights for its many local lights, and the sun can still go through Virtual Shadow Maps. We explain Lumen, Nanite and Virtual Shadow Maps in Nanite and Lumen in Unreal Engine 5, explained. 5.8 also brought Lumen Lite in beta, a medium-quality global illumination setting that Epic says is twice as fast as Lumen’s high quality.

What COLONIZED does with it

The development build of COLONIZED, on Unreal Engine 5.8, does not use MegaLights. It uses Nanite, Lumen for global illumination and reflections, with software tracing by default, and Virtual Shadow Maps. Hardware ray tracing has been tested in the engine but is not on by default. MegaLights appears only in code comments.

The reason is in the scenes. A planet is lit mostly by one star, and the sun is exactly the light Epic recommends handling with Virtual Shadow Maps. Where the game needs many small lights, such as the emergency beacons blinking in the debris of the Cementerio de Aura, the development build draws them through per-instance material data, without real lights and without sending anything over the network. What the released game will offer in its graphics options has not been announced; when that changes, it will be in the devlog.

If you are thinking about hardware rather than rendering paths, our PC optimisation and video memory guide covers what we have measured so far, and DLSS, Frame Generation and Reflex, explained covers the NVIDIA side.