Fortnite on Unreal Engine 5: can Steam Deck handle Epic’s next-gen tech?

Valve’s Steam Deck revolutionized PC gaming, its custom 15W AMD processor exceeding expectations and doing a great job of delivering a triple-A portable experience – but Unreal Engine 5 might just be its toughest challenge yet. day, due to its Nanite micro-geometry and RT-Lumen based illumination. This is next-gen – or rather, current-gen – so the Deck’s ability to handle it is key to its longer-term prospects. To put this to the test, we decided to see if we could run the latest version of Fortnite with all of these features in play – and the results were surprising.

I went into this one with little optimization. The Valley of the Ancient demo was a slideshow on the Deck, while the Matrix Awakens City Sample demo with big cuts still runs mostly in sub-20fps territory. But remarkably, Fortnite is playable, even handicapped by a number of issues that are holding the machine back.

In fact, making the game work is hard enough. The biggest problem of all is that due to Fortnite’s lack of compatibility with anti-cheat technology, the game won’t work on SteamOS at all, which means you need to install Windows to make it work. The second problem is a warning from Epic when starting the game, telling us that our GPU driver is outdated and performing suboptimally – which isn’t going to help our cause.

Unreal Engine 5 with RT Material Lumen, Nanite and Virtual Shadows enabled on Steam Deck and stacked on Xbox Series S.

When it comes to settings, I’ve generally opted for high settings across the board – a basic attempt to largely mimic the Xbox Series S. To be clear, these settings choices are not intended to produce settings optimized for Fortnite on Steam Deck. Using ray-traced lighting and Nanite is not a good idea. If it worked in Steam OS, you’d be using the more streamlined modes and looking to target 60fps. Our experiments today are something quite different: it’s about testing the viability of UE5’s cutting-edge features on the Deck.

Early results were too good in that the performance was actually quite impressive – and by stacking Steam Deck against Xbox Series S in a linked multiplayer game, the reasons became clear. Despite selecting the software version of Lumen (inline with consoles), it didn’t seem to work at all. The only way to achieve globally equivalent overall illumination was to use the RT Lumen hardware setting. On the one hand, using RT hardware when consoles ignore it is quite the feat, but on the other hand, there are reasons why Epic chose to go with the software solution – it’s faster – and this option for faster performance was not available to me in my tests.

So there’s good news and bad news in terms of our overall results with Fortnite on the Deck. We can get close to 30fps on Deck – even using the RT hardware – but the bad news is that we have to run super time resolution in performance mode to do so, which means – surprisingly perhaps – we let’s actually go to 360p. TSR is really quite impressive on the one hand, but on the other hand I can’t help but wonder if we could get better image quality and more stable performance if we had the option of using the RT software, inline with console builds.

Using Fortnite’s replay system, we can compare perfectly matched gameplay footage using any combination of settings we like – so I started by comparing the various super time resolution options, from 720p in performance mode TSR, up to native 720p with TAA. The TSR variants may be closer than you think, while native 720p using TAA is obviously a lot slower – but on the other hand it renders RT to the pixel count broadly in line with the S-series. being, 19 to 24 fps is pretty impressive for a handheld with a 15W APU serving both CPU and GPU. TSR’s resilience is also impressive, bearing in mind that in performance mode it only goes to 360p. It may just be due to the way Fortnite presents, but even that looks good on a portable screen. Even so, a consistent playback of 30fps or more is still elusive, even on the lowest resolution option we have here.

I ran these frame rate tests with v-sync disabled, allowing valid benchmarking of the different permutations. TSR performance on the clip weighs in at 30.04 fps – but remember the frame rate is both above and below that average. Switching to Balanced TSR results in an 8% performance drop for an average of 27.6 fps, while the much cleaner TSR quality mode can only muster 87% of the performance mode figures with an average of 26, 2fps. Native 720p resolution delivers 22 fps, or 73% of the throughput of TSR performance.

Going into this experiment, I was looking to replicate the results I saw on the Deck running Metro Exodus Enhanced Edition on Windows (there’s no RT support in SteamOS yet), stacked against Xbox Series S, with resolution compromise and a frame rate reduction from 60fps to 30fps. It seems that the settings I have chosen have a small deficit of detail and I was interested to see that the RT hardware option presents a clearly RT-based lighting solution that still looks quite different from the S-series. Even thus, we’re on our way to a decent 30fps experience on the Steam Deck that in motion is quite similar to the Series S experience – and I think there are clear avenues to improve performance (the software Lumen not working properly being the big disappointment of my tests).

Performance comparison using different flavors of super temporal resolution upscaling, stacked against native 720p with TAA.

Another thing to consider is that while it’s great to use all the high-end features of the UE5 together, it’s not a must – certainly not Fortnite-based, at least. Lumen lighting can be turned off for a simpler, flatter alternative. Alternatively, Nanite Geometry or Virtual Shadows can also be disabled. There are options to increase performance, but I guess the question is how much future UE5 titles focusing on consoles will target 60fps in the first place and whether fallbacks will work well enough if, for example, RT lighting should be off. There’s also the issue of resolution: TSR works great with Fortnite in upscaling from absurdly low resolutions, but how would more detailed visuals fare?

And of course, each game – even those running on the same engine – can have very different hardware requirements. Right now there’s only Fortnite to test, but at least with our first working example of an actual UE5 game, the Steam Deck’s only 1.6 teraflops of peak GPU compute associated with its cluster Reduced CPU (compared to Sony and Microsoft consoles) seem to be at least capable of running in a playable state.

It was an interesting experience at the time – and I can’t wait to see what the next UE5 title will be that uses Lumen and Nanite, and how well it will work on the Steam Deck. Running future UE5 titles on SteamOS will also be an interesting challenge, bearing in mind that by using Windows on the Deck, we are effectively operating in UE5’s “home territory”. This should mean good or bad things for the Deck. Either way, I’m really looking forward to seeing how scalable UE5 is and how well Steam Deck can handle this new wave of demanding titles. In the meantime: UE5, Lumen and Nanite running on a handheld with a power envelope of just 15W? It can be done!

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