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

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.

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.

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 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.

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.

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?

It was a sad day when UO introduced Trammel.

>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?

When I was in high school, I played a lot of UO. It was actually the last computer/video game I ever played regularly, because I convinced myself as a teenager that I was addicted to it and needed to drop it "cold turkey" to focus on academics and extracurriculars.

(A sign of the times for the late-1990s nostalgics: I sold my UO account on eBay for a few thousand dollars and an MTG Mox Pearl. I owned a bunch of virtual real estate, e.g. a UO tower on an island only accessible via moongate. The high bidder "threw in" a Mox Pearl as a kind of informal escrow, to make sure I completed the account transfer after getting paid.)

Before I dropped UO from my life, I discovered UOX. I was learning C++ and UOX was a great way for me to practice my emerging C++ skills.

My clearest memory of feeling the power of programming was when I created a mod for my UOX server that allowed me to drop an unlimited number of interconnected and color-coded moongates all over my server, creating something akin to the feeling of the game "Portal," but long before Valve released "Portal."

It was after having a blast with UOX that I decided to dig into programming much more. Somehow, the UOX server mod made programming feel "real" for me in the way my prior forays into coding simply didn't.

That led to me learning Python -- as a way of toying around with the Slackware Linux server I had in my basement. I left C++ behind, but it was an important stepping stone for me. Now, decades later, learning Python was probably the single most important decision of my life in childhood. (See e.g. https://amontalenti.com/about)

UOX is such a cool project. UO was a really ahead-of-its time internet game, as well. Great memories. Thank you.

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.

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.).

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.

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

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

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

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.

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.

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.

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.

Ultima Online launched in September 1997. The first "offline emulator" launched in October. Emulators became playable by mid 1998. https://www.uox3.org/history/timeline.txt

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.