o11c

You've clearly thought about the problem, so the solutions should be relatively obvious. Some less obvious ones:

• It is impossible to make TCP reliable no matter how hard you try, because anybody can inject an RST flag at any time and cut off your connections (this isn't theoretical, it's actually quite common for long-lived gaming connections). That leaves UDP, for which there are several reliability layers, but most of them are not battle-tested - remember, TCP is most notable for congestion-control! HTTP3 is probably the only viable choice at scale, but beware that many implementations are very bad (e.g. not even supporting recvmmsg/sendmmsg which are critical for performance unlike with TCP; note the extra m)
• If you don't encrypt all your packets, you will have random middleware mess with their data. Think at least a little about key rotation.
• To avoid application-centric DoS, make sure the client always does "more" than the server; this extends to e.g. packet sizes.
• Prefer to ultimately define things in data, not code (e.g. network packet layouts). Don't be afraid to write several bespoke code-generators; many real-world serialization formats in particular have unacceptable tradeoffs. Make sure the core code doesn't care about the details (e.g. make every packet physically variable-length even if logically it is always fixed-length; you can also normalize zero-padding at this level for future compatibility. I advise against delta-compression at this level because that's extra processing you don't need).
• Make sure the client only has to connect to a single server. If you have multiple servers internally, have a thin bouncer/proxy that forwards packets appropriately. This also has benefits for the inevitable DDoS attacks.
• Latency is a bitch and has far-ranging effects, though this is highly dependent on not just genre but also UI. For example "hold down a key to move continuously through the world" is problematic whereas "click to move to a location" is not.
• Beware quadratic complexity, e.g. if every player must send a location update to every player.
• Think not only about the database, but how to back up the database and how to roll back in case of catastrophe or exploit. An append-only flat file has a lot going for it; only periodic repacking is needed and you can keep the old version for a while with a guarantee that it'll replay to identical state to the initial version of the new file. Of course, the best state is no state at all. You will need to consider the notion of "transaction" at many levels, including scripting (you must give me 20 bear asses for me to give), trading between players, etc.
• You will have abuse in chat. You will also have cybersex. It's possible to deal with this in a privacy-preserving way by merely signing chat, not logging it, so the player can present evidence only if they wish, but there are a lot of concerns about e.g. replays, selective message subsets, etc.
• There will be bots, especially if the official client isn't good enough.
• It's $CURRENTYEAR; write code for IPv6 exclusively. There are sockopts for transparently handling legacy IPv4 clients.
• Client IP address is private information. It is also the only way to deal with certain kinds of abuse. Sometimes, you just have to block all of Poland.
• Note that routing in parts of the world is really bad. Sometimes setting up your own dedicated connection chain between datacenters can improve performance by orders of magnitude, rather than letting clients use whatever their ISP says. If nesting proxies be sure to correctly validate IPs.
• Life is simpler if internal stuff listens on a separate port than external stuff, but still verify your peer. IP whitelisting is useless except for localhost (which, mind, is all of 127.0.0.0/8 for IPv4 - about the only time IPv4 is actually useful rather than a mere mirage).

True, speed does matter somewhat. But even if xterm isn't the ultimate in speed, it's pretty good. Starts up instantly (the benefit of no extraneous libraries); the worst question is if it's occasionally limited to the framerate for certain output patterns, and if there's a clog you can always minimize it for a moment.

Speed is far from the only thing that matters in terminal emulators though. Correctness is critical.

The only terminals in which I have any confidence of correctness are xterm and pangoterm. And I suppose technically the BEL-for-ST extension is incorrect even there, but we have to live with that and a workaround is available.

A lot of terminal emulators end up hard-coding a handful of common sequences, and fail to correctly ignore sequences they don't implement. And worse, many go on to implement sequences that cannot be correctly handled.

One simple example that usually fails: \e!!F. More nasty, however, are the ones that ignore intermediaries and execute some unrelated command instead.

I can't be bothered to pick apart specific terminals anymore. Most don't even know what an IR is.

I guess I forgot to mention the other implicit difference in concerns:

When you are a game, you can reasonably assume: I have the user's full focus and can take all the computing resources of their device, barring a few background apps.

When you are an application, the user will almost always have several other applications running to a meaningful degree, and those eat into available resources (often in a difficult-to-measure way). Unfortunately this rarely gets tested.

I'm not saying you can't write an app using a game toolkit or vice versa, but you have to be aware of the differences and figure out how to configure it correctly for your use case.

(though actually - some purely-turn-based games that do nothing until user enters input do just fine on app toolkits. But the existence of such games means that game toolkits almost always support some way of supporting the app paradigm. By contrast, app toolkits often lack ready support for continuous game paradigms ... unless you use APIs designed for video playback, often involving creating a separate child "window". Actual video playback is really hard; even the makers of dedicated video-playing programs mess it up.)

The problem with XCB is that it's designed to be efficient, not easy. If you're avoiding toolkits for some reason, "so what if I block the world" may be a reasonable tradeoff.

There's tends to be one major difference between games and non-game applications, so toolkits designed for one are often quite unsuitable for the other.

A game generally performs logic to paint the whole window, every frame, with at most some framerate-limiting in "paused" states. This burns power but is steady and often tries hard to reduce latency.

An application generally tries to paint as little of the window as possible, as rarely as possible. Reducing video bandwidth means using a lot less power, but can involve variable loads so sometimes latency gets pushed down to "it would be nice".

Notably, the implications of the 4-way choice between {tearing, vsync, double-buffer, triple-buffer} looks very different between those two - and so does the question of "how do we use the GPU"?

1, Don't target X11 specifically these days. Yes a lot of people still use it or at least support it in a backward-compatible manner, but Wayland is only increasing.

2, Don't fear the use of libraries. SDL and GTK, being C-based, should both be feasible from assembly; at most you might want to build a C program that dumps constants (if -dM doesn't suffice) and struct offsets (if you don't want to hard-code them).

Even logging can sometimes be enough to hide the heisgenbug.

Logging to a file descriptor can sometimes be avoided by logging to memory (which for crash-safety includes the possibility of an mmap'ed file, since the kernel will just take care of them as long as the whole system doesn't go down). But logging from every thread to a single section of memory can also be problematic (even without mutexes, atomics can be expensive and certainly have side-effects) - sometimes you need a separate per-thread log, and combine in the log-reader tool.

I don't remember the last time I used ctrl-C. It's always select or "+y.

True, but successfully doing dynamically-linked old-disto-test-environment deployments gets rid of the real reason people use static linking.

DNS-over-TCP (which is required by the standard for all replies over 512 bytes) was unsupported prior to MUSL 1.2.4, released in May 2023. Work had begun in 2022 so I guess it wasn't EWONTFIX at that point.

Here's a link showing the MUSL author leaning toward still rejecting the standard-mandated feature as recently as 2020: https://www.openwall.com/lists/musl/2020/04/17/7 ("not to do fallback")

Complaints that the differences are just about "bug-for-bug compatibility" are highly misguided when it's useful features, let alone standard-mandated ones (e.g. the whole complex library is still missing!)

I haven't managed to break into the JS-adjacent ecosystem, but tooling around Typescript is definitely a major part of the problem:

• following a basic tutorial somehow ended up spending multiple seconds just to transpile and run "Hello, World!".
• there are at least 3 different ways of specifying the files and settings you want to use, and some of them will cause others to be ignored entirely, even though it looks like they should be used.
• embracing duck typing means many common type errors simply cannot be caught. Also that means dynamic type checks are impossible, even though JS itself supports them (admittedly with oddities, e.g. with string vs String).
• there are at least 3 incompatible ways to define and use a "module", and it's not clear what's actually useful or intended to be used, or what the outputs are supposed to be for different environments.

At this point I'm seriously considering writing my own sanelanguage-to-JS transpiler or using some other one (maybe Haxe? but I'm not sure its object model allows full performance tweaking), because I've written literally dozens of other languages without this kind of pain.

WASM has its own problems (we shouldn't be quick to call asm.js obsolete ... also, C's object model is not what people think it is) but that's another story.

At this point, I'd be happy with some basic code reuse. Have a "generalized fibonacci" module taking 3 inputs, and call it 3 ways: from a web browser on the client side, as a web browser request to server (which is running nodejs), or as a nodejs command-line program. Transpiling one of the callers should not force the others to be transpiled, but if multiple of the callers need to be transpiled at once, it should not typecheck the library internals multiple times. I should also be able to choose whether to produce a "dynamic" library (which can be recompiled later without recompiling the dependencies) or a "static" one (only output a single merged file), and whether to minify.

I'm not sure the TS ecosystem is competent enough to deal with this.