Show HN: Server-rendered multiplayer games with Lua (no client code)

85 pointsposted a month ago
by brunovcosta

61 Comments

kibbi

a month ago

Interesting approach! I've thought about a similar method after reading about the PLATO platform.

When playing astro‑maze, the delay is noticeable, and in a 2D action game such delays are especially apparent. Games that don’t rely on tight real‑time input might perform better. (I'm connecting from Europe, though.)

If you add support for drawing from images (such as spritesheets or tilesheets) in the future, and the client stores those images and sounds locally, the entire screen could be drawn from these assets, so no pixel data would need to be transferred, only commands like "draw tile 56 at position (x, y)."

(By the way, opening abstra.io in a German-language browser leads to https://www.abstra.io/deundefined which shows a 404 error.)

brunovcosta

a month ago

Yeah.. As people are playing and I'm watching their feedbacks it is becoming clear to me that the main source of input delay comes from the distance to the server.. the whole game is running in a single machine in SFO, so it makes total sense this bad exp in europe

I think this is inevitable unless I add some optimism/interpolation in the client

Also, thanks for the feedback! I will fix the Abstra landing page

try https://www.abstra.io/en instead

ModernMech

a month ago

You're running this at the airport?

fragmede

a month ago

It's a Googleism. The datacenter is referred to by the nearest airport because airport codes make it straightforwardsto know roughly where the DC is.

Bender

a month ago

For completeness sake this is not strictly a Google thing. Many companies use airport codes for their data-centers.

fionic

a month ago

Cool! Besides the productizing or making a framework, I’m trying to understand if this is different than the elementary idea (which probably every game dev who worked on game networking has tinkered with) of sending inputs to the server and then sending player positions back to all the clients…? I think even smaller footprint would be position: two or three floats x,y(,z) instead of shapes too? Anyway this is always fine for very low latency environments where client side prediction, lag comp etc would not be required. Thanks for sharing, I might give it a try! sorry if I’m missing something.

brunovcosta

a month ago

You're correct

My approach lives in some place between video streaming and data streaming in terms of performance

It's not intended to be faster than a proper client that brings a lot of logic and information that diminish the amount of information required to be transfered

My proof of concept is more about: Can my dev exp be much better without relying on the video streaming approach? (which is havier)

ghxst

a month ago

IMO eliminating as much client side authority as possible is a very good foundation for MMOs where the latency is acceptable or factored into all aspects of the game (looking at old school runescape as an example). Very cool project!

Matheus28

a month ago

Client-server multiplayer games are already kind of a very specialized type of video playback if you squint a bit (you're transmitting entities rather than pixels).

This method of multiplayer you propose is inferior in basically every way: you can't do client-side prediction to make inputs feel smoother, and non-trivial scenes will surely take up more bandwidth than just transmitting entity deltas.

Thaxll

a month ago

"Impossible to Cheat"

Let me tell you that there is cheating in cloud rendering solution ( Stadia, AWS Luna ect ... )

So 100% there is cheating in your solution.

It's trivial to read the screen.

brunovcosta

a month ago

You're right

Especially with today's computer vision

The cheating I'm more protected (just as stadia, etc..) is regarded to client/code exploitation

which we don't have to worry about in this approach

allthatineed

a month ago

BYOND/Space Station 13 is built upon this model.

Sprite sheets are png with ztxt blocks with meta/frame info and a list of drawing operations to be done to construct vsprites based on any runtime server side operations done on the sprites.

There is limited client coding via popup Web view windows and a few js apis back to the client but nothing you can build too much off of.

(SS14 brings this model to an open source c# framework called The Robust Engine but has some limitations related to maintainer power tripping over who should be allowed to use their open source project.)

brunovcosta

a month ago

Amazing! Never heard of this byond/ss13/14

Thank you for the reference!

aetherspawn

a month ago

The latency is a little intense from Australia … but surprisingly not as bad as I thought it would be.

It was playable.

I wonder if you can use speculative execution to play the game a few frames ahead and then the client picks what to display based on user input, or something like that.

Each frame is 16ms, so you’d have to work ahead 6 frames to conquer the nominal latency of around 100ms, which may actually be 200ms round trip.

(In that case, something like Haskell would be a good candidate to build a DSL to build the decision tree to send to the JS client…)

lurkshark

a month ago

What you’re describing is called “rollback netcode”. It’s a pretty cool chunk of theory, usually used for fighting games which are extremely sensitive to latency. This explainer has some nice graphic demos

https://bymuno.com/post/rollback

dustbunny

a month ago

It's a common misconception that this is only used in fighting games. This technique was developed first in Duke Nukem, and then exploited heavily by Carmack in Quake, and subsequently refined and built upon in other AAA FPS games, specifically for the local player movement and shooting.

ThatPlayer

a month ago

I don't think it's quite the same. Rollback netcode is like lockstep netcode, where the entire game is simulated locally and only inputs are networked. Since it's still only input being networked, network drops (or slow computers) affect everyone, requiring the simulation to slow down. Not just fighting games, but RTS games would do this. If you've ever played Starcraft/Warcraft 3 where it would freeze when a player disconnected.

With rollback/lockstep, there's no need for a server simulation at all. Most games are not doing that: the client's local simulations are less important than the server's simulation, even missing information (good to prevent wallhacks). Any dropped packets are handled with the server telling the client the exact positions of everything, leading to warping. Dropped packets and latency also only affect the problem player, rather than pausing everyone's simulations.

aetherspawn

a month ago

This is awesome and exactly what it needs, but good luck creating a language that’s “signal driven” enough to encode it and then send all the possible states to the client.

If you were able to make it, it would be kind of a Hail Mary moment for making easy server games without the latency.

Neywiny

a month ago

It could help visually but you'll still have 200ms between you and your next door neighbor's actions

6r17

a month ago

Cheating with AI will be possible even with server side rendering ; nvidia has released models able to learn to play - it's going to be very difficult to detect whether it's an AI or a human ; very impressive however

nkrisc

a month ago

That’s a very different kind of cheating though. The kind of cheating this effectively makes impossible is cheating where a player has more information than they’re intended to have.

If someone makes an AI that plays the game as a good player, then it’s effectively indistinguishable from a real player who is good. If they make it super-humanly good, then it would probably be detectable anyway.

It’s still fair in the sense that all players have the same (intended) information per the game rules.

throwaway894345

a month ago

I’m also curious if an AI could process the screen feed quickly enough to compete in first-person shooter games. Seems like it would be difficult without extremely high end hardware for the foreseeable future?

ModernMech

a month ago

I had students build this kind of thing in 2020 by screenshotting the game and processing it with a standard OpenCV pipeline. No GenAI needed.

throwaway894345

a month ago

Thank you for educating me. How does OpenCV work from the perspective of recognizing things in an image? Is there some kind of underlying model there that learns what a target looks like or not?

ModernMech

a month ago

The way they did it, they were writing an aimbot. So the pipeline was:

- take a screenshot

- run massive skeletal detection on it to get the skeletons of any humanoids

- of those skeletons, pick a target closest to the player

- for that target, get coordinates of head node

- run a PID to control the cursor to where the head node is located

- move the camera one frame, repeat the whole process. If you can fit that pipeline to 16ms it can run in real time.

throwaway894345

a month ago

Wow, that's fascinating. Were they able to fit the whole thing inside the 16ms frame?

ModernMech

a month ago

oh yeah, with little problem, especially with a GPU it's not hard at all.

Scion9066

a month ago

There's already models specifically for things like identifying players in Counter-Strike 2, including which team they're on.

Someone has even rigged up a system like that to a TENS system to stimulate the nerves in their arm and hand to move the mouse in the correct direction and fire when the crosshair is over the enemy.

We are definitely already there.

Thaxll

a month ago

It already exists.

ASalazarMX

a month ago

If there's enough players, the server could segregate them in tiers. All superhuman players would eventually end up competing between themselves.

tnelsond4

a month ago

Since you're doing this is rust, try experimenting to see what would happen if you did zstd compression using a dictionary on the data you're sending back and forth, it might give you a performance benefit.

brunovcosta

a month ago

I will definitely try it!

I'm using Gzip since it comes with all browsers hence a easy approach

That said, I will find som zstd decompressor for js/wasm and try!

edit:

I just added and the difference was huge! Thank you!

2001zhaozhao

a month ago

> - Streaming game primitives instead of pixels, which should be much lighter - Server-side rendering makes cheating basically impossible

This doesn't work in 3D. Unless you have the server do the work of the GPU and compute occlusion, you'll end up sending data to the client that they shouldn't be able to have (e.g. location of players and other objects behind walls)

nkrisc

a month ago

Theoretically couldn’t you send each client its data after performing occlusion culling based on each one’s camera?

Don’t some competitive games more or less already do this? Not sending player A’s position to player B if the server determines player A is occluded from player B?

I seem to recall a blog post about Apex Legenda dealing with the issue of “leaker’s advantage” due to this type of culling, unless I’m just totally misremembering the subject.

Regardless, seems like it would work just fine even in 3D for the types of games where everyone has the same view more or less.

cmrdporcupine

a month ago

"We stream drawing primitives instead of heavy pixels or complex state objects."

This is cool ... but I suspect just pushing video frames like Stadia etc did is just as efficient these days and a lot less complicated to implement and no special client really needed. Decent compression, and hardware decode on almost every machine, hardware encode possible on the server side, and excellent browser support.

MarsIronPI

a month ago

On the other hand, you could take a list of primitives from, say, the JS Canvas API, come up with a format that can encode all of them and use that as your protocol. Bam, with that you get one client for any game that uses JS Canvas.

brunovcosta

a month ago

That's exactly my approach! I'm sending canvas commands instead of pixels, which makes things faster

That said.. I don't think stadia could do that since it's not opinionated about the game engine. Unless they go really deep on the graphics card instructions instead, but then it becomes comparable to pixel rendering I guess

ftgffsdddr

a month ago

Is the source code available?

efilife

a month ago

Doesn't seem like it

emmelaich

a month ago

Reminds me of the cave X11 games. For game play I'd suggest slowing it way down.

brunovcosta

a month ago

good feedback! I'm seeing people really struggly with the control lag + speed.

I'm always biased since I test locally with no delay when developing :)

LoganDark

a month ago

are there any affordances for prediction or replay? you could try to help network latency by having the server resimulate a small period of time roughly equivalent to the client's network delay - it's not perfect without client-side prediction but it could help

brunovcosta

a month ago

It's possible, but harder than traditional client/server paradigm since the client here is generic so the predictablity should be based on something other than heuristics

I'm thinking about simple ML to predict inputs and feedbacks. Since the amount of data generated in the streaming is massive and well structured, it looks like a possible approach

chasebrignac

a month ago

Sick! And the game is fun too! I’m sending to my brother who is a junior game dev.

ycombinatrix

a month ago

Is this how Stadia was supposed to work?

brunovcosta

a month ago

Not exactly, since they aren't opinionated in the game engine, they can't control what "primitives" are being used to render.. they probably just encode video

ycombinatrix

a month ago

I guess you're right, all their talk about working with game developers was probably just to get the games working on their hardware.

ingen0s

a month ago

Might be the greatest thing I have seen made in like 10 years

user

a month ago

[deleted]

duduzeta

a month ago

Cool!! I'm trying to test here, but other ships keep attacking me and I don't know how to shoot :s

brunovcosta

a month ago

Amazing! hahaha.. Tip: Arrows + Z (shoot)

kibbi

a month ago

In my case, Z for shooting works only rarely. Usually nothing happens. How does the game code query the key?

iku

a month ago

i think, after shooting, it has to recharge. When recharged, the ship momentarily blink-expands in yellow. This means it is ready to fire again.

But sometimes, i been left without a recharge, and without shooting, and I don't know why.

brunovcosta

a month ago

exactly as @iku commented.. there is a cooldown time between shots.. it pulses when you're ready and resets when you try before it's loaded!

It seems that I should add a better visual feedback haha