[Animats]

The underlying technology doesn't have to be obsolete to have legacy code problems. Linux, Windows, GCC, Microsoft Office - all have serious internal problems from legacy code, and are tough to maintain.

It's not so bad for big projects with enough staff. It gets tough when the legacy code does something hard, and the maintenance team doesn't really understand why something was done in some way.

Second Life, the virtual world, has that problem. It's written in C++, and some very good people wrote it about 10-15 years ago. They're all gone. The people who maintain it today are struggling to fix serious bugs that have been outstanding for 5-8 years. It's not just "legacy", it's "not web-like". It's a distributed system with tens of thousands of servers in one data center. It's a tightly coordinated soft real time system. There's a huge amount of in-memory state, which is changeable in real time yet is constantly being backed up. This is totally alien to people who only know transaction-type web-based systems. So they can't hire anybody and have them be productive quickly.

[bjt]

Doesn't that describe a lot of MMOs too, though? The inventory/transaction systems seem like they'd have similar needs (but with a LOT more items in the Second Life database). And the in-world state is a lot more variable than in an MMO. But compared to MMOs, those seem more like differences in degree than differences in kind. Programmers with that background should be able to get productive a lot quicker than web devs I'd imagine.

[Animats]

Most major games are built on one of a few game engines (Unity, UE4, etc.) which have their own ecosystems. People become Unity or UE4 experts. They have forums, conferences, tech support. SL is its own pocket universe.

Second Life is divided into "regions", 256m on a side, each managed by a separate process constantly communicating with its neighbors. This geographical distribution system is unique to Second Life. User avatars and objects can move from one region to another. You can look across region boundaries. Running Mono programs inside objects are stopped, frozen, copied across the network, and restarted on a different machine.

Most big-world MMOs cheat somehow so that they don't have to really solve the distribution problem. They're often sharded, so that the number of players that can interact is limited. Or they're smaller. Second Life's world is 100x the size of GTA V. Or they're portal based; you can only get somewhere via a controlled portal. In Second Life, you can fly over the whole world. (Mostly. Fast vehicles hit bugs the devs have been unable to fix for a decade. Another "legacy" problem.)

This is what the machinery for a "Ready Player One" or "Snow Crash" world looks like.

It's not parallel enough, and the servers keep running out of CPU time on the main thread. Everything then gets sluggish in world. The system needs an overhaul to be more parallel internally on the core functions, and that's really hard, expensive, and needs a dev team the company lacks. Yet another legacy problem.

The technology is all unique to this one system. The only thing that works even vaguely like this is the new Spatial OS from Improbable, which took 150 people to develop, is proprietary, and hasn't been shown to really scale yet. We'll know late this year, as Nostos, a new game from China, rolls out, how well it really scales. That's the first AAA title to use Spatial OS. Spatial OS has a deal with Google where it has to run on Google Cloud servers, which is scaring off most of the big game development shops. That costs too much, and betting your business on a lesser Google product usually ends badly.

Hence the recruiting problem Linden Lab faces. You want to tie your career to this one-off strange system?

[bjt]

I'm familiar with Second Life's distinctive traits. I played there for years, and did contract programming for the Linden Department of Public Works for a couple of them (including coding around those janky region crossing issues you mention).

They pay an incredibly high price for some design decisions that I think users don't even get much value from. It turns out that most users would rather have a private island than live on a continuous continent where neighbors are always putting up eyesores. If you were to start with that fact, remove the requirement that private regions even exist on the global map, and let them spin down when no one's home, then you could give paying users a lot more space for their money while also reducing the company's spend on servers.

While I take your point about work on Second Life not being super transferrable to any of the AAA game engines, it seems like it would be very transferrable to creating such engines themselves. And what engineer wouldn't want to help build the world of Snow Crash or Ready Player One?

I think the deeper problem is that Linden Lab has stopped prioritizing investment in the SL platform. They've set their sights on creating VR-focused Sansar instead. But it's tough to convince people to move over to a new world when it means leaving behind the bigger community, the bigger economy, and all the clothes in their inventory.

[Animats]

It turns out that most users would rather have a private island than live on a continuous continent where neighbors are always putting up eyesores.

Linden Lab tried that. That's what Sansar is. It averages 13 concurrent users on Steam. Maybe some more who signed up outside Steam, but under 100. Sansar is a "VR game level loader", not a world like SL. Somebody creates a level map, and others can visit, but not change much. Sansar has a Star Wars prop museum, a Ready Player One prop museum, etc. They look great. You visit once, and you're done.

Other VR game level loaders are SineSpace and High Fidelity. (High Fidelity just gave up, and "pivoted to enterprise".) They also have user counts in the 2-digit range, but worse content than Sansar. The hook for that market segment was supposed to be VR headsets, which turned out to be a niche product. Even VRchat, after a surge in 2017, dropped to about half its initial peak and is stuck at a few thousand concurrent users. Facebook Spaces? Whatever happened to that?

Meanwhile, Second Life continues to plug along, with 30,000 to 50,000 users connected. That's about where GTA V online is, and would be 11th place on Steam if SL was on Steam. SL was maybe twice as big at peak, 7-10 years ago.

Hence the legacy code problem. It runs, it's profitable, it has a significant user base, and it needs improvement.