RTX Mega Geometry in Alan Wake 2 – improved, faster, more efficient ray tracing

It’s been over six years since the first consumer-level graphics cards arrived that supported hardware accelerated ray tracing and while hardware has improved massively since the launch of Nvidia’s Turing architecture in 2018, this has been matched with innovations in the software space. RTX Mega Geometry was revealed at CES 2025 with a range of compelling demos, but now we have our first example of the technology in a shipping game: Alan Wake 2. There are quality, efficiency and performance upgrades but perhaps the biggest surprise in our testing is that it’s the RTX 20-series and 30-series GPUs that benefit most.

Let’s start with the basics – what is RTX Mega Geometry? This requires an understanding of how RT actually works. As things stand, every game essentially creates two 3D worlds – the world as you see it in-game and a secondary ‘BVH structure’ which is typically a lower detail rendition of the environment. BVH stands for bounding volume hierarchy. Rays are projected into the BVH structure and their direction is then calculated. As you might imagine, RT itself is already computationally expensive, so creating and tracing into the BVH structure adds to the cost. Furthermore, there are limitations – while the game world may be animated, it does not mean the BVH will be, potentially leading to mismatches and loss of visual quality.

Enter RTX Mega Geometry, which is basically a new API allowing for a new type and hierarchy to the BVH structure, containing the game world’s geometry and assets. The focus is on animated geometry, support for a larger amount of level-of-detail transitions and adaptive tesselation where the amount of actual geometry per frame is constantly changing. Mega Geometry adds a new level to the BVH structure: the CLAS or Cluster Acceleration Structure. While the extra complexity adds to the time to trace rays, there’s an extraordinary increase in detail and support for animated environments.

RTX Mega Geometry is essentially an Nvidia-branded version of a fundamental change to RT APIs that will almost certainly be adopted by all vendors. In a world where mesh shading, Epic’s Nanite and the basic requirement for animated environments come to the fore, the existing DXR APIs aren’t really fit for purpose – all of which brings us to the specific implementation found in Remedy’s Alan Wake 2.

This title is an excellent use-case for RTX Mega Geometry as the game world is rich in detail via mesh shading and is highly animated. In Alan Wake 2, geometry is actually physically moving and transforming like a skinned character mesh, as opposed to ‘faking’ it with a vertex shader. All of which makes the implementation difficult with an existing BVH structure. A number of optimisations are in place to increase performance – such as decreasing the animation rate the further detail is from the player. The first 10 metres are full rate, followed by half, third and quarter rate further into the distance. On PS5, this is halved further. The closest detail runs at half rate, and only characters run at full rate.

RTX Mega Geometry has clear and measurable improvement. Like for like, VRAM usage was reduced by around 300MB in my testing. In practical terms, the RTX 4060 now runs 42 percent faster using direct lighting and low quality indirect lighting as it’s no longer running out of VRAM. Meanwhile, CPU performance improves too. On a lowly Ryzen 5 3600, I saw a 14 percent improvement to frame-rate in the custom bench sequence we built for our GPU reviews.

For GPU performance, I benched with FSR upscaling and low path tracing with direct lighting, finding that the RTX 2080 Ti at native 1080p has a 13 percent improvement to performance. Outside of the benchmark scene and in actual gameplay at 1080p using DLSS quality mode, running through the first brings performance in the mid 20fps region up to 30fps. Moving on to the RTX 3080, performance improves by 10 percent. At 1080p DLSS quality mode, frame-rate is now north of 40fps and no longer dips beneath. Intriguingly, however, I noted no real performance gains whatsoever in the same tests running on RTX 4090 and RTX 5080. However, you do get all the quality gains I talked about previously.

Beyond RTX Mega Geometry, the new version of Alan Wake 2 also ships with a new ultra ray tracing mode, but before I go on, I should stress that I still recommend optimised settings for those looking to experience RT in the game – so that’s low RT with direct lighting enabled. This delivers the biggest bang for the buck, with anything further more in the realm of diminishing returns.

Ultra RT is a nice addition to the settings though, adding extra fidelity that essentially adds final flourishes to the RT feature set. That starts with improvements to transparency ray tracing, allowing for more accuracy in the effect with multiple bounces. Secondly, indirect lighting is enhanced, resulting in better shading and more accurate bounce lighting. All told, both new features offer relatively conservative improvements but looking forward to an era where PCs can run this game with ease, it’s nice to see ‘luxury’ features that scale into the capabilities of the hardware of tomorrow.