[jackb4040]

Best comment from last time this got posted:

I kept on reading expecting to see motion prediction, multiversion, or similar given the name and focus on games, but no. This is a totally normal database, designed for low latency and with support for WASM stored procedures. You can host your own server or they will rent you one. Don't get me wrong, this looks very nice. It looks like a solid building block for persistent worlds in multiplayer games. You'll just have to do your lag masking netcode yourself.

https://news.ycombinator.com/item?id=43593913

[cloutiertyler]

Just to copy in my response from there too:

I'm Tyler (guy in the video). In BitCraft we currently implement client-side prediction outside of SpacetimeDB.

However, we DO plan to add automatic client-side prediction as a feature for SpacetimeDB in the near-ish future! Because all your server-side logic is in Wasm modules, we plan to run an embedded version of SpacetimeDB to execute the server logic on the client. As long as the server and client agree on the changes to the data we can reconcile the transactions, otherwise we'll rollback. Notably, we can do this with only partial state on the client!

We can also do deterministic simulation if you have total knowledge of the game state with this solution as well.

[kriper]

How would you simulate physics, pathfinding, animation state on the server using this tech? Do you have to ditch your engine (do I have to reimplement what unity/unreal gives me for free?) ?

[ncr100]

Cool, jumping in as a noob to multiplayer dev, so currently for BitCraft MMORPG simulation, e.g. to prevent "god-mode flying", would be done outside the server.

Q How is that coordinated with the SpacetimeDB? Is there a penalty, or perhaps a correction applied to the malicious client (and replicated to listening clients) in the case a hacker modifies their movement illegally?

Tx for sharing your time btw!

[Rohansi]

Since SpacetimeDB would be your backend (game client <-> SpacetimeDB) you would need to verify the inputs to your reducers to prevent cheating. Not really different from anything else.

[zinlencer]

But that's completely different from how Unreal typically does it. Movement is client-side predicted and server authoritative out of the box. How does SpacetimeDB even know the collisions of my level?

If I were to cheat and disable all wall collisions on the client. An Unreal server would roll me back, to all other people it would look like I'm walking into the wall. How do you even get SpacetimeDB to run Unreal's runtime (because movement kind of depends on deterministic results for frames). How does SpacetimeDB get hold of the assets (collisions)?

[Rohansi]

I am also skeptical of SpacetimeDB for the same reason. There is no game engine helping you do any simulation and that makes development harder. Your (server-side) assets would somehow need to be synced to SpacetimeDB which possibly means you can't use your editor tools to design them anymore.

As a service backend+database the concept is cool and probably useful. But I don't see it being good at being a game server.

[whizzter]

Reading/hearing talks from people doing server backends there is many half insane things being done to keep servers and persistence in check, and everyone still a different custom solution.

A common scenarios:

- "Game-server" using "regular" server+DB frameworks, often works but seldom in real-time scenarios.

- Realtime Game-servers (with in-memory state, sometimes supporting rollback,etc) that then has persistence more or less as an afterthought (duplicating state management between client<->server<->persistence)

What spacetime tries to do (and my current experiment) is to merge the server and DB to move persistence _performance_ concerns into the backend process.

We _rightfully_ moved databases out of server processes for easier management and safety in the 90s, but since f.ex. SQLite has been a bit of a resurgence because the usercode was in a managed language and wasn't as likely to cause a corruption issue.

WASM is a great enabler here because it allows the server/DB to sandbox the logic-code even in "unsafe"/realtime languages from the more precarious DB parts of the process so we don't have to risk data-safety even as we move back to co-locating server-state and persistence data within the same process.

[whizzter]

Prediction can definitively be argued that it belongs in a layer above it, multi-version/rollback/reconciliation should be integrated however and I don't really see any mention of it from a quick skimming. (really need to take a closer look later today).

[gafferongames]

[flagged]

[tomhow]

Hey, can you please make your substantive points without shallow dismissals or snark? This is in the site guidelines: https://news.ycombinator.com/newsguidelines.html. Unfortunately you posted a few comments in this thread that have crossed that line.

If you know more than others as a professional multiplayer game developer, that's great, but in that case the thing to do is to share some of what you know, so others can learn. If you don't want to do that, that's fine, but in that case please don't post. Putdowns and swipes only degrade the discussion.

[gafferongames]

Excuse me Tom, please stop with ad hominem and attack the topic not the poster.

[gafferongames]

Tom I'm afraid you're misreading the tone of my posts and their character.

I could post anything objectively true in this thread like "the sky is blue", and some idiot will post a one sentence response that in fact it's not. This idiot likes to be the last person getting snark in responding to a completely reasonable statement of fact or opinion by an expert in the space.

What I do differently is that yes, I do reply to the snark with a rebuttal. Is this rebuttal snarky? Potentially, but is it earned? Definitely.

You're moderator so let me speak to you that way. If you don't let people rebut bullshit in this comment section, you'll just end up with a bunch of uninformed discourse, where the final word is made by some idiot, who doesn't even make multiplayer games and everyone ends up thinking the sky is fucking green. This has real world consequence when future game developers try to build games on poorly made technology, which ruins game studios and people's lives.

Then again, it's hacker news, and what do a bunch of wannabe startup guys know about making games in the first place. Unskilled and unaware of it. Moderate away sir!

[dang]

You can "rebut bullshit" without being aggressive or nasty. If someone else is wrong, it's enough to provide correct information respectfully. Putting others down, or slamming their work in a hostile way, doesn't help and degrades this community badly.

https://news.ycombinator.com/newsguidelines.html

Btw, it's quite common for commenters to underestimate the provocation in their own posts and overestimate the provocation in other people's posts. Those two factors can multiply into quite a skew in perception (https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...). I wonder whether this might be a bit of a factor here, if you really don't see how aggressively your comments were coming across.

[gafferongames]

In my experience providing detailed information in a response in the comment section on this particular topic (game development and networking) in hacker news comments simply creates more surface area for nitpicking and arguing in response, so I keep to short responses and rebuttals.

In the future, I don't feel that writing anything more here on this topic is a worthwhile use of my time.

[insraq]

Just want to chime in that although this comment is a bit harsh, it does hold a lot of truth. As a game netcode engineer, most of my time is spent on latency hiding techniques and its consequences (for example, we use rollback netcode and lots of efforts are spent on minimizing visual/sound glitches when mispredict, rollback and reconcile). There are lots of middleware that help with this (eg. Photon, SnapNet, etc) but in general there's no silver bullet - it's highly gameplay specific. Even for the same game, the solution can vary depending on different trade-offs (i.e. budget, correctness/anticheat).

As to how to store the game state in memory, it's usually not something that needs much thinking: it's simply done the same way (or similar) as the game's client code. After all, netcode is mostly about efficient state replication and this saves CPU time when replicating it across clients - and gives more CPU time for minimizing bandwidth (like delta encoding, quantization, etc). If you want, you can utilize some techniques like ECS to optimize for CPU cache locality, but it affect gameplay code a lot and would need to get the whole team onboard.

Also, I just noticed the username "gafferongames" - Glenn's blog[1] has been a must-read for netcode engineers. It helped me a lot when I started working on netcode in the 2010s

[1] https://gafferongames.com/

[TeMPOraL]

Well, I'm not a professional gamedev, nor did I ever do much multiplayer code, but:

1) AFAIR, the ECS patterns family[0] originally came from MMORPG world, and boiled down to designing your game state to work well with relational databases;

2) Around 6 years ago, while toying with yet another (see [0]) take on ECS for a simple game, and wondering how to query stuff efficiently, it dawned on me that the code I'm writing is basically implementing spacial indices and other such concepts from relational DB world. At that point, I thought to myself, "why continue wasting time Greenspunning[1] a database for the internal state, when I could use a real one?", and followed by "you know what I really need next? An in-memory SQLite database to store all my runtime game state!".

I didn't get very far with my experiment due to constraints of adult life, but I did prove that I can build a basic Roguelike skeleton (2D tile map, entities, walls, collisions) while storing all state in SQLite, and have it run at 60 FPS with half of the frame time to spare for other things, on moderately powerful machine (as of 6 years ago), all without too much optimization (Common Lisp with FFI bindings to libsqlite3 + a simple RLU cache in front of queries).

So it's not at all a stupid idea, IMO :). I would test it further if I had the time.

--

[0] - The term means different things to different people. I've seen at least three distinct gamedev design patterns claiming the name ECS for themselves, all conceptually incompatible with each other. More, if you also consider "whatever Unity/Unreal/Godot/... calls ECS".

[cloutiertyler]

We can and plan to handle the complex lag masking netcode as well. We've just focused so far on games that don't need very sophisticated lag compensation

[gafferongames]

Planning to support complex lag masking netcode as a TODO is not a good sign.

[cloutiertyler]

TODO does not imply no plan or that we haven't thought deeply about the problem. Prioritization is imperative when you're building an MMORPG and a new database with a small team for both.

[gafferongames]

How can you think deeply and plan for something when you don't know what don't know. You can only really understand these things when you've taken a game using these latency hiding techniques into production, and then after this, you'll probably realize that some of your original ideas were wrong. Where does this leave SpacetimeDB then?

[cloutiertyler]

I'd be happy to schedule a chat to talk with you about our plans if you'd like! I'd love to get your thoughts.

[stronglikedan]

just because someone doesn't think and plan just like you do, doesn't mean they will not succeed

[Aeolun]

I mean, they are dogfooding their own database. If they’re making a MMO game with it presumably the game has latency masking netcode, even if it isn’t in part of the database.

[pphysch]

Seems too biased and harsh. The best lag masking and clientside prediction systems I've experienced as a player are those that are closely integrated with the idiosyncratic gameplay mechanics. I would never expect SpacetimeDB to have a one-size-fits-all solution to this, nor for it to be the central focus of their product.

[gafferongames]

Game development is not something you learn by playing games.

[pphysch]

You will implement terrible lag masking and clientside prediction if you aren't looking at it from the UX perspective, because that is literally the only reason these features exist, to trick players into thinking the game signals are moving faster and with greater frequency through the network than is physically possible. Perhaps you would make better games if you considered the user perspective.

[XCSme]

As a gamedev, I don't understand the use-case for SpacetimeDB.

Is it simply to be able to persist the game state?

[neuroelectron]

Wasm? What a great idea.