Show HN: Moongate – Ultima Online server emulator in .NET 10 with Lua scripting

This is such a good observation. UO had a real economy and social hierarchy because power wasn't handed to you. You could spend months as a fisherman or tailor and still have a meaningful experience. The gap between a grandmaster swordsman in full plate and a guy selling fish at the Britain bank was enormous, and both of them were having fun.

Modern MMOs are theme parks where everyone gets the same ride (with pay per win). UO was a living world where your role emerged from what you chose to do, not from a quest marker telling you where to go next.

Being a legendary blacksmith was the whole point. Where crafting was the end game state for crafters. The gear produced was max durability, max dmg, max armor rating. The furniture for your castle had to come from someone, somewhere.

The whole point of the game was to live in this fantasy world, not beat it. There were no quests. No antagonist. Just good and evil and everyone in between. For once I wish a studio would take this to heart and build something like that again. Minecraft exploded due to this sandbox nature. However, you still got to give players a shovel and a bucket.

UO was the best online game for me. All others stand in its shadow. It was the most "free" in terms of what you could do and the appeal was the non-gamification.

I loved Everquest and World of Warcraft but those didn't feel "raw" enough for me.

The Realm is my dark horse submission for best MMO. (Yea, yea, yeah Meridian 59 and Underlight too)

I never played it, but from what I've heard, it sounds like the original Star Wars: Galaxies MMO (before they added all the NGE stuff?) had fairly mundane / commoner roles as well.

It sounds like a fan-driven reboot of this game has a fairly decent following, in a very similar way to what UO experiences? It feels like there is still player desire to have mundane sorts of immersive RPG experiences in this way.

Sounds like Vanilla WoW before Blizzard killed 40 man hardcore raiding. Only a few guilds on the whole server had the top gear.

I'll forever chase the dragon that is the joy of playing UO. I want to quit my job and play it 24/7.

Was it actually that hard?

I played on the JP/KR asian servers in a PK/APK/PVP guild so maybe it was just my bubble but it was pretty common to see players with 7 skills maxed out. If I remember correctly

- sparring

- swordsman or fencing

- magic

- magic resistance

I don't remember the rest. It's not quick or easy like modern games, but we would regularly power level each other's alts and it took maybe 2 weeks to max out all 7 skills? We had a bear trapped in the guild house so we could power level wrestling and other combat skills.

My preferred methods at the time, sneaking/breaking into houses, stealing, and ganking/PKing unsuspecting souls (emphasis on graveyards, dungeons, and miners). Stealing items, often the offensive spell reagents, out of someone's bag before a fight made for no shortage of quality interactions.

It was a sad day when UO introduced Trammel.

Haven and Hearth has "sprucecaps" and "hermits". The elite in these games arise when they are willing to work in groups, willing to use violence against isolated players, and willing to use automation.

Haven't put any time in MMORPGs for 15 years, but aren't there still "exclusive" guilds that do things regular players can only aspire to?

Yup. Tibia you had this too. People begging in the depot for gold and "itens plx"

yes, this really nails it. UO didn't chase "endgame content" which, imo, is the bane of today's multiplayer games. Designers expect everyone to max out and reach the end of the road so everyone is the same in the end.

I can relate to this part in terms of visuals:

>It's very different from modern games, where each player looks like the fantasy version of a Marvel super hero

But isn't this true for most games?

>UO was the only game that I've ever played where you had "commoner" players. A lot of players failed to scale up, or to obtain top notch equipment.

I guess the main example I'm thinking of is Path of Exile. There is such a massive difference between your average player and the top tier. Or even not the top tier but enthusiasts.

I mean almost by definition most people wont have top notch equipment?

I think you'd like Arc Raiders.

So: I took most of the infrastructure from the my first attempt at moongate (https://github.com/moongate-community/moongate, which failed miserably along with https://github.com/tgiachi/Prima). From there, I had a good starting point to quickly build the foundations. I had already done the Lua scripting part in another project (https://github.com/tgiachi/Lilly.Engine). Codex helped me with all the testing, implementing functionality and creating tests, so at least I have a good sparring pattern. For the data import part (which I called FileLoaders), I took the logic from ModernUO. For the items part, I created a script (scripts/dfn_*.sh) to import items from POL! Thanks for the compliments! The way I am, if I fixate on something, it becomes an obsession!

I forgot to mention, the entire web part in React was done by Codex. I hate developing frontends!

That’s awesome to hear! Actually UOX3 is one of the inspirations behind Moongate. The way it approached the server architecture and scripting was really interesting and it influenced some of the ideas I’m exploring in the project.

Projects like UOX3 are a big part of the history of the Ultima Online emulator scene, so it’s great to hear from someone who helped maintain it.

This is a very fun idea. Would also be very interesting to see if one could have a system where talking to an NPC could alter the world.

One maybe obvious way would be that asking for rumors will actually creates the scenario that the NPC describes.

I am interested please write me on GitHub!

Ultima Underworld is a fantastic game.

Thanks! Yeah, one of the main motivations was exactly that — after years working with legacy UO codebases where networking, persistence, and game logic were deeply intertwined, I wanted to see what a clean-slate approach would look like with modern .NET.

On sector sync bursts — this is something I'm actively tuning. Right now when a player enters a new sector, we sync all ground items and mobiles in the surrounding sectors (configurable radius). For busy areas that can mean a lot of packets at once. The current approach is:

  - Sector enter sync only sends the delta  sectors the player wasn't already seeing, so a simple move into an adjacent sector doesn't resync everything
  - Sectors close to the player (within 1 of center) are always resynced because the UO client silently drops items beyond its visual range (~18 tiles), so you need to re-send them when the player comes back
  - The outgoing packet queue handles the actual send, so the game loop isn't blocked waiting for network I/O

  That said, there's definitely room for prioritization (mobiles first, then nearby items, then distant items) and spreading the sync across multiple ticks instead of one burst. It's on the roadmap.

  On NativeAOT — honestly, both. The single-binary deployment is great for Docker (small image, instant startup), but the real win is predictable performance. No JIT warmup, no tiered compilation surprises
  mid-session. For a game server where you care about consistent tick timing, eliminating that variable is worth it. The tradeoff is you lose some runtime flexibility, but source generators fill most of that gap
  (packet registration, serialization, etc.).

>Curious about the sector-based delta sync — how do you avoid packet bursts when a player enters a busy area with lots of items and mobiles?

doesn't look like there is much going on to protect packet bursts there aside from smart-ish proximity sector loading. the work is done at boundry.

dove into it because i have been recently working on frustrum spawning to reduce net burst in a similar project, was kind of curious if something similar was used as a method to pre-warm the upcoming sector but I didn't catch anything.

fun and easy to read. thanks op and parent for getting me to look through it.

> SphereServer

Throwback!

Pretty sure I still have the source to SphereServer sitting somewhere on my NAS. It was my first exposure -- in early high school -- to coding in a group and operating a Linux server.

Thanks! The logo was a happy accident. I wanted something simple that felt like the moongates (so and so :) from the original game. I'm not really a video person. But here's what's working today: login flow, character creation, world movement with delta sector sync, auto-generated doors from map statics (that actually open), Lua scripting for item behaviors, snapshot persistence, and a React admin UI for server management.

I'll probably add a short demo gif or video to the README at some point, but for now the best way to see it is to clone it and run it

Ha, you're absolutely right from a CS perspective! it's a protocol reimplementation, not emulation in the traditional sense. I've thought about this too. "Server emulator" stuck in the UO/MMO (other example Mangos is "Wow emualtor") community because RunUO and similar projects used the term 20 years ago and it just became the standard label. At this point fighting it feels like your Wikipedia edit war, technically correct but practically hopeless. !

  That said, I'll take the nitpick as a compliment :) means you actually read the project description. Thanks for the kind words!

> I've long been irritated by the use of the term "server emulator" in gaming contexts. Technically these projects are just reimplementations of a proprietary networking protocol. Nobody calls Samba a "server emulator" because it reimplements the Windows file sharing protocol, because Samba isn't "emulating" anything from the perspective of the traditional definition of "emulator" in computer science.

I think the distinction is a lot greyer than the black/white you propose.

The very first popular online games used servers mostly to redistribute (and maybe time sync) packets from clients. There is no standard way to to do that. Player-created servers did their best to emulate the official servers logic but it was indeed impossible to replicate it perfectly.

e.g. when breaking up large maps into sectors, the official server might broadcast your location and projectiles X units away and emulators would broadcast it X + 500 units away, which could have an impact on gameplay.

Emulator feels fitting when there is no official server spec to reimplement.

edit: emulator also feels appropriate where servers are responsible for NPC activity or quest-like mechanics. This goes beyond implementing a network protocol. The gameplay is massively impacted.

> I certainly do find new slang introduced by gen Z like "he got the riz!" to be quite cringey

This is interesting to me, if only because it's such a natural bit of slang. Given that it's a shortened form of "charisma", this one just Makes Sense to me! I figure it'd be incredibly cringe for me to use at my age, but it's a good term IMO.

UO Outlands has been pretty popular for a few years. They’ve implemented a lot of custom aspects (specialties), craft, new dungeons, land, as well as weekly quests and events. My brother and I play it a few hours a week. It’s incredibly popular for the nostalgia and its player base seems to be pretty consistent. It reminds me of early UO where your exploring, learning, and dying a lot. And there tends to be players everywhere you go.

Thanks! There are still a few active shards out there, mostly us "old guys" in our 40s chasing the nostalgia of our teenage years. UO has a way of never really dying. Combat and skills are still a ways off, but the foundation is solid enough that I'm adding features every week (in spare times,) I'll keep pushing updates!

Most active is UO Outlands. Several thousands players?

They've reworked a lot of systems and it's basically 100x better than original UO.

There are several systems in place, which original devs wouldn't even dream of and saying that, official Ultima Online is still running. :D

It's PvP server, but with balanced PvP which really works for everyone. Not like original devs, they just dropped PvP because cookie-cutter players cried.

UO outlands (most popular shard) has pretty alright support and guides for linux

Same here! tinkering with private servers is what got me into programmig in the first place. There's something about reverse-engineering a game protocol at 15 that hooks you for life. Thanks for the kind words on the name and art!

Thank you! RunUO in 2003 was the golden era. I started little bit early (1999 with 56k). The community is small but still alive, and projects like ModernUO have kept things moving forward. Moongate is my take on rethinking the architecture from scratch while keeping the same spirit. Glad to see people still care about this stuff! :*

Thanks! I've been developing in .NET for 20 years and it's come a long way , from the Windows-only Framework days to what it is now. NativeAOT, cross-platform, incredible performance. And if you've never tried it on Apple Silicon the M4 chips are absolutely insane. The server compiles to a single native binary and runs like a dream on ARM.

hank you! That separation was a very deliberate choice I've seen firsthand how quickly things degrade when packet handling leaks into game logic.

You're touching on a real pain point. Right now the Lua boundary does show measurable overhead under load, especially with per-tick callbacks across many entities (doors, spawners, etc.). MoonSharp's interop cost adds up when you're calling into Lua thousands of times per tick.

I'm actively looking at batching script invocations per tick and capping the budget so a heavy script wave can't blow up tail latency. The goal is to keep the game loop deterministic if Lua eats too much of the tick budget, defer the rest to the next tick rather than letting the whole loop stall.

It's one of those problems where the architecture gives you a clean place to solve it (the boundary is explicit, so you can meter it), but the solution still needs work. Appreciate you calling it out — good toknow others think about the same tradeoffs.

Luanti(previously Minetest) does a similar trick: c++ core/game engine, but all the game logic is in lua.