Helion: A modern fast paced Doom FPS engine in C#
67 comments
·June 10, 2025bob1029
qingcharles
I also see the guys from Intel constantly stabbing at all these low-level types to optimize them too. There are optimizations in .NET 10 for processors that aren't even released yet.
marhee
I suspect it's part of the fun? A way to really learn something?
There's also another hint:
// THIS FILE WAS AUTO-GENERATED. // CHANGES WILL NOT BE PROPAGATED. // ----------------------------------------------------------------------------
(Of course this could be a result of something having nothing to do with the contents of the file, but maybe the author has to meta library that can generate the types in different languages).
There seems to be fixed-precision variants of the vector types as well which seems to be not available in the .NET framework.
Plus, of course, you can't add your specifics needs to library types (like the fixed precision). They are closed to modification.
I am just guessing, of course.
That being said, it would also make total sense to use the .NET types.
jabart
It looks like these types were code-gen from something else.
https://github.com/Helion-Engine/Helion/commit/e6affd9abff14...
accoil
Further down in the commit there's a Generators project that has the VectorGenerator class.
Disposal8433
> [a diff with] +4620 -1454 [lines]
Someone should learn some CS and then how to make proper commits.
tester756
This is pull requests, there are commits
Additionally this is generated code.
golergka
Computer science has literally nothing to do with good commit habits.
animal531
I posted further down about Bepu Physics v2: https://github.com/bepu/bepuphysics2
It heavily uses numerics and the performance is amazing.
materialpoint
Historically the .NET and XNA vector types have been seriously lacking for real graphics development, and they still don't even provide swizzling. It's likely that this project predates .NET numerics by many years, and anyone who has had a pet project for long enough will learn to avoid becoming too dependent on libraries and platforms that will die out.
energywut
I wonder if it can play through MyHouse.wad. Which, if you haven't seen before, is an incredible art piece.
https://www.youtube.com/watch?v=5wAo54DHDY0
If you've read House of Leaves, do yourself a favor and check it out.
uncircle
If you talk about myhouse.wad, you must link the video of John Romero himself playing it: https://youtu.be/gIl_TqFJNO8?si=H4o6m-RbH2rpX2FG
BLKNSLVR
Thank you for the, so far, half-day rabbit hole...
Agreed, it is an incredible art piece, and now I want to go find a copy of House of Leaves.
low_tech_love
He used Eviternity 2 as an example, my personal GOTY for 2024. Check it out if you haven’t!
tines
Oh man, House of Leaves is amazing. Danielewski has my respect.
wiseowise
I’m also curious about this.
ngrilly
Finally, a good example of a modern C# code base that is open source, and that doesn't look like the equivalent of J2EE in C#.
aeonik
Thanks for your comment, made me want to check it out, and yea it's really clean code.
tester756
I wanted to provide link to Ryujinx repo, but I've found that Nintendo threaten them and they had to close the project :(
necrosyne
Allegedly, Nintendo chose to buy them off with millions of dollars to suspend development instead of pursuing legal action.
lrae
Is there any source on that?
All I'm seeing is they got their hands on the domain, which can be (and was in the past) just part of whatever settlement they agreed on, and the game press spinned that into "Nintendo bought Ryujinx".
Cieric
This looks interesting and I'm going to take a look later. Just a minor nitpick up front though, I think the performance graph should be a bar graph instead of a line graph. Mainly since the in-between states don't have much meaning as you can't be half way between 2 different gpus.
ogurechny
Those discussions are a bit misleading. Original Doom updates its state only 35 times a second, and ports that need to remain compatible must follow that (though interpolation and prediction tricks are possible for visual smoothing of the movement). Rendering engine is also completely orthogonal to polygon-based 3D accelerators, so all their power is unused (apart from, perhaps, image buffers in fast memory and hardware compositing operations). Performance on giant maps therefore depends on CPU speed. The point of this project is making the accelerator do its job with a new rendering process.
Though I wonder how sprites, which are a different problem orthogonal to polygonal rendering, are handled. So, cough cough, Doxylamine Moon benchmarks?
kfuse
"Rendering engine is also completely orthogonal to polygon-based 3D accelerators"
Software rendering engine, yes (and even then you can parallelize it). But there is really no reason why doom maps can't be broken down in polygons. Proper sprite rendering is a problem, though.
ogurechny
Sure, that has been done since the late '90s release of the source code, both by converting visible objects to triangles to be drawn by the accelerator (glDoom, DoomGL), or by transplanting game data and mechanics code into an existing 3D engine (Vavoom used recently open-sourced Quake).
However, proper recreation of the original graphics would require shaders and much more modern extensive and programmable pipelines, while the relaxed artistic attitude (or just contemporary technical limitations) unfortunately resulted in trashy y2k amateur 3D shooter look. Leaving certain parts to software meant that CPU had to do most of the same things once again. Also, 3D engines were seen as a base for exciting new features (arbitrary 3D models, complex lighting, free camera, post-processing effects, etc.), so the focus shifted in that direction.
In general, CPU performance growth meant that most PCs could run most Doom levels without any help from the video card. (Obviously, map makers rarely wanted to work on something that was too heavy for their systems, so the complexity was also limited by practical reasons.) 3D rendering performance (in non-GZDoom ports) was boosted occasionally to enable some complex geometry or mapping tricks in popular releases, but there was little real pressure to use acceleration. On the other hand, the linear growth of single core performance has stopped long ago, while the urges of map makers haven't, so there might be some need for “real” complete GPU-based rendering.
atmavatar
Even just updating the graphs would be helpful. There appear to have been several releases since 0.9.2.0, including a bump from .NET 7 to .NET 8 (and a bump to .NET 9 in dev).
The more recent .NET versions by themselves are likely to have some impact on the performance, let alone any changes in Helion code between versions.
kevingadd
Might make sense to use a logarithmic scale for the graphs too, it's hard to tell what speed the other ones are since they're compressed so far down.
_0ffh
It's a Doom engine, and they missed the opportunity to call it "Hellion"??
bigbuppo
And with the name Hellion they could also go down the Judas Priest rabbit hole.
null
dimitropoulos
the Doom in TypeScript types project wouldn't have been possible without Nick and Helion - I owe Nick a huge thanks! He helped with some of the more obscure parts of the engine and also helped make a super small WAD that is what the game eventually ran in.
Legend.
LoganDark
Doom in TypeScript types is amazing. Thank you for losing your mind for the rest of us :)
yodon
Impressive C# performance!
dax_
Microsoft has really been putting a lot of focus on improving it with each release. I love reading through the blog articles for each major release, that outline all the performance improvements that were done: https://devblogs.microsoft.com/dotnet/performance-improvemen...
runevault
A warning for those not in the know, the performance improvement posts famously give mobile browsers trouble because they are so massive. All because the extent of the improvements is so great (along with the amount of detail the posts go into about the improvements).
ddingus
I just viewed the one linked above, and the coupla second render delay at first aside, the post displayed nicely, at full frame rate.
Old Note 9, Chrome and Firefox.
Non flagship mobile devices could very well choke on one of those pages, but most newer devices should display these pages with little grief.
qingcharles
And if you look at the PRs for the core, there are Intel people hacking away at the low-level routines too; to make it run better on their latest server CPUs.
animal531
Go and have a look at Bepu Physics v2: https://github.com/bepu/bepuphysics2
It can be quite performant these days, sadly I'm stuck developing in Unity Mono C# which is quite a bit behind.
bee_rider
Finally I can play Doom on my 2khz monitor.
dataflow
2 kHz monitor? Is that a joke, or a typo, or real?
mawadev
The Benchmarks look a bit sketchy... is the frame uncapped for all the other engines and has vsync been disabled? It's a very odd graph to look at, but great performance regardless
c-hendricks
There's a link to a spreadsheet with the actual numbers, and there doesn't appear to be any capping: https://docs.google.com/spreadsheets/u/0/d/19INwMjrppDO-n90H...
reverseblade2
I have seen some use case for MemoryStream, why not use RecyclableMemorysStream instead?
thomasqbrady
How does licensing work, here... could you use this to develop an indie game and sell it?
gr4vityWall
Yes. Only requirement is that your game code is Free Software (GPLv3).
kasajian
Not sure what the question is. The License is clearly stated.
gcr
No, it’s GPL3, so your game must be open-source.
If the authors wanted to protect engine development while allowing indies to sell games made on it, they would have picked LGPL or a more permissive license.
detaro
since when do people not sell GPL games?
energywut
You are technically correct, and I believe the GPL doesn't cover the assets for the game (levels, art, audio, etc.), but I suspect there aren't many GPL licensed games out there for sale that have sold enough copies to make developing them worthwhile financially.
I'd love to be wrong, so if you have a few examples, I'm all ears.
whizzter
You can sell them on PC, but any dream of console releases are dead in the water as Sony,etc forbids distribution or even code using their SDK's to be shared publicly.
patrick4urcloud
i will give a try.
I am curious if the author considered use of the built-in numerics library over hand-rolling types like Vector4F.
All of the methods defined here:
https://github.com/Helion-Engine/Helion/blob/20300d89ee4091c...
Are available in the kitchen sink:
https://learn.microsoft.com/en-us/dotnet/api/system.numerics...
Same idea applies to methods like GetProjection, which could be replaced with methods like:
https://learn.microsoft.com/en-us/dotnet/api/system.numerics...
Advantages of using this library are that it is uses intrinsics (SIMD) to accelerate operations. There is a lot of Microsoft money & time that has been invested into these code piles.