Highly Performant & Scalable Ultima Online Server Emulator https://www.modernuo.com
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Kamron Batman b191498569
feat: Adds Feature Flag System (#2328)
## Feature Flag System

A runtime feature flag system for dynamically enabling/disabling game systems and blocking specific game elements
without server restarts.

### Overview

Two types of controls:

1. Feature Flags - Named boolean flags that gate entire systems (trading, PvP, vendors, housing, etc.)
2. Dynamic Blocks - Block specific gumps, items, skills, or spells by type

All changes are persisted to JSON, broadcast to online staff, and bypass-able by administrators.

### Predefined Flags
```
┌─────────────────┬──────────┬─────────────────────────────────────┐
│      Flag       │ Category │             Description             │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ player_trading  │ Economy  │ Allow secure trades between players │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ vendor_purchase │ Economy  │ Allow purchasing from NPC vendors   │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ vendor_sell     │ Economy  │ Allow selling to NPC vendors        │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ player_vendors  │ Economy  │ Allow player vendor interactions    │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ bank_access     │ Economy  │ Allow bank box access               │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ house_placement │ Housing  │ Allow new house placements          │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ boat_placement  │ Housing  │ Allow new boat placements           │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ bulk_orders     │ Crafting │ Allow bulk order deeds              │
├─────────────────┼──────────┼─────────────────────────────────────┤
│ pvp_combat      │ Combat   │ Allow player vs player combat       │
└─────────────────┴──────────┴─────────────────────────────────────┘
```

### Commands

#### Feature Flags
```
┌────────────────────────────────────────────────────┬───────────────────────┐
│                      Command                       │      Description      │
├────────────────────────────────────────────────────┼───────────────────────┤
│ [FeatureFlag <key> on|off|toggle|info              │ Manage a feature flag │
├────────────────────────────────────────────────────┼───────────────────────┤
│ [FF <key> on|off                                   │ Shorthand alias       │
├────────────────────────────────────────────────────┼───────────────────────┤
│ [FeatureFlag <key> create <category> <desc>        │ Create a custom flag  │
├────────────────────────────────────────────────────┼───────────────────────┤
│ [FeatureFlag <key> delete                          │ Delete a custom flag  │
├────────────────────────────────────────────────────┼───────────────────────┤
│ [FeatureList [flags|gumps|items|skills|spells|all] │ List all flags/blocks │
├────────────────────────────────────────────────────┼───────────────────────┤
│ [FeatureAdmin                                      │ Open the admin gump   │
└────────────────────────────────────────────────────┴───────────────────────┘
```

#### Gump Blocks
```
┌────────────────────────────────┬──────────────────────────────────────────────────────┐
│            Command             │                     Description                      │
├────────────────────────────────┼──────────────────────────────────────────────────────┤
│ [BlockGump <typeName> [reason] │ Block a gump type from displaying                    │
├────────────────────────────────┼──────────────────────────────────────────────────────┤
│ [UnblockGump <typeName>        │ Remove a gump block                                  │
├────────────────────────────────┼──────────────────────────────────────────────────────┤
│ [ListGumps [self]              │ List open gumps on a player (for finding type names) │
└────────────────────────────────┴──────────────────────────────────────────────────────┘
```

#### Item Blocks
```
┌────────────────────────────────────────────────┬───────────────────────────────┐
│                    Command                     │          Description          │
├────────────────────────────────────────────────┼───────────────────────────────┤
│ [BlockItemUse <typeName|target> [reason]       │ Block item use                │
├────────────────────────────────────────────────┼───────────────────────────────┤
│ [BlockItemEquip <typeName|target> [reason]     │ Block item equipping          │
├────────────────────────────────────────────────┼───────────────────────────────┤
│ [BlockItemContainer <typeName|target> [reason] │ Block container access        │
├────────────────────────────────────────────────┼───────────────────────────────┤
│ [UnblockItemUse <typeName>                     │ Remove use block              │
├────────────────────────────────────────────────┼───────────────────────────────┤
│ [UnblockItemEquip <typeName>                   │ Remove equip block            │
├────────────────────────────────────────────────┼───────────────────────────────┤
│ [UnblockItemContainer <typeName>               │ Remove container access block │
└────────────────────────────────────────────────┴───────────────────────────────┘
```
Item block commands create an entry if one doesn't exist, or flip the relevant flag on an existing entry. Unblock
commands only clear their specific flag -- the entry is removed when all flags (use/equip/container) are off.

#### Skill & Spell Blocks
```
┌──────────────────────────────────────┬──────────────────────┐
│               Command                │     Description      │
├──────────────────────────────────────┼──────────────────────┤
│ [BlockSkill <SkillName> [reason]     │ Block a skill        │
├──────────────────────────────────────┼──────────────────────┤
│ [UnblockSkill <SkillName>            │ Remove a skill block │
├──────────────────────────────────────┼──────────────────────┤
│ [BlockSpell <SpellTypeName> [reason] │ Block a spell        │
├──────────────────────────────────────┼──────────────────────┤
│ [UnblockSpell <SpellTypeName>        │ Remove a spell block │
└──────────────────────────────────────┴──────────────────────┘
```

### Architecture

- Static bool classes for hot-path checks (no dictionary lookups): ServerFeatureFlags (Server project) and
ContentFeatureFlags (UOContent)
- Synced automatically by FeatureFlagManager.SyncStaticFlag() when flags change
- Predefined flags loaded from Distribution/Configuration/FeatureFlags/default-flags.json
- Runtime state persisted to Configuration/FeatureFlags/*.json (flags, gump-blocks, item-blocks, skill-blocks,
spell-blocks)
- Admin gump with tabbed UI for managing all block types, per-entry PropertiesGump editing, and pagination
- All staff at AccessLevel.GameMaster+ bypass dynamic blocks; AccessLevel.Administrator+ bypass feature flags

### Hook Points

Hook: Player trading
Location: Mobile.OpenTrade
Mechanism: ServerFeatureFlags.PlayerTrading
────────────────────────────────────────
Hook: PvP combat
Location: Mobile.CanBeHarmful
Mechanism: ServerFeatureFlags.PvPCombat
────────────────────────────────────────
Hook: Bank access
Location: BankBox.Open()
Mechanism: ServerFeatureFlags.BankAccess
────────────────────────────────────────
Hook: Vendor buy/sell
Location: BaseVendor
Mechanism: ContentFeatureFlags.VendorPurchase/Sell
────────────────────────────────────────
Hook: Player vendors
Location: PlayerVendor
Mechanism: ContentFeatureFlags.PlayerVendors
────────────────────────────────────────
Hook: House placement
Location: HousePlacement.Check()
Mechanism: ContentFeatureFlags.HousePlacement (returns BadRegionTemp)
────────────────────────────────────────
Hook: Boat placement
Location: BaseBoatDeed.OnDoubleClick/OnPlacement
Mechanism: ContentFeatureFlags.BoatPlacement
────────────────────────────────────────
Hook: Bulk orders
Location: SmallBOD/LargeBOD
Mechanism: ContentFeatureFlags.BulkOrders
────────────────────────────────────────
Hook: Gump display
Location: GumpSystem.SendGump
Mechanism: FeatureFlagManager.IsGumpBlocked
────────────────────────────────────────
Hook: Item use
Location: PlayerMobile.AllowItemUse
Mechanism: FeatureFlagManager.IsItemUseBlocked
────────────────────────────────────────
Hook: Item equip
Location: PlayerMobile.CheckEquip
Mechanism: FeatureFlagManager.IsItemEquipBlocked
────────────────────────────────────────
Hook: Container access
Location: BaseContainer.DisplayTo
Mechanism: FeatureFlagManager.IsContainerAccessBlocked
────────────────────────────────────────
Hook: Skill use
Location: PlayerMobile.AllowSkillUse
Mechanism: FeatureFlagManager.IsSkillBlocked
────────────────────────────────────────
Hook: Spell casting
Location: Spell.Cast / Spellbook.CastSpellRequest
Mechanism: FeatureFlagManager.IsSpellBlocked
2026-02-07 12:02:57 -08:00
.config feat: Adds SerializableFieldChanged option (#2324) 2026-02-01 21:28:26 -08:00
.github feat: Upgrades networking to use io_uring. (#2315) 2026-02-01 16:02:32 -08:00
Distribution/Data feat: Adds Network Packet Documentation (#2302) 2026-01-01 17:52:56 -08:00
docs chore: Fixes 0x78 and min client version for packets.html (#2322) 2026-01-31 10:58:13 -08:00
Projects feat: Adds Feature Flag System (#2328) 2026-02-07 12:02:57 -08:00
.editorconfig chore(docs): Adds UnmanagedDataReader & BinaryFileReader documentation (#1968) 2024-10-01 17:07:51 -07:00
.gitattributes fix: Adds migration checks to CICD, updates dependencies, adds Fedora 37, alpine 3.17 support (#1309) 2022-12-22 12:12:47 -08:00
.gitignore feat: Moves logger to a separate assembly for reuse (#2001) 2024-12-30 20:25:34 -08:00
azure-pipelines.yml feat: Adds .NET 10 / C# 14 support. (#2258) 2025-11-11 11:26:34 -08:00
CODE_OF_CONDUCT.md Create CODE_OF_CONDUCT.md 2020-05-05 08:51:39 -07:00
CONTRIBUTING.md chore(license): Removes CLA requirement. All contributors moving forward will retain copyright. (#2038) 2024-12-31 02:52:58 -08:00
Directory.Build.props feat: Adds .NET 10 / C# 14 support. (#2258) 2025-11-11 11:26:34 -08:00
FAQ.md docs: Updates FAQ for time zone issues. (#1368) 2023-03-10 00:18:36 -08:00
global.json feat: Adds .NET 10 / C# 14 support. (#2258) 2025-11-11 11:26:34 -08:00
LICENSE Fixes more line ending issues (#267) 2020-09-27 13:54:56 -07:00
mkdocs.yml chore: Fixes github pages (#2303) 2026-01-01 19:35:35 -08:00
ModernUO.sln fix: Updates Visual Studio version in solution file to Visual Studio 2026 (#2285) 2025-12-01 14:46:36 -08:00
publish.cmd fix: Fixes publishing (#1808) 2024-05-31 12:59:59 -07:00
publish.sh fix: Fixes publishing (#1808) 2024-05-31 12:59:59 -07:00
README.md feat: Upgrades networking to use io_uring. (#2315) 2026-02-01 16:02:32 -08:00
rider-settings.zip Cleanup/Housekeeping (#242) 2020-09-12 15:31:21 -07:00
Rules.ruleset chore(docs): Adds UnmanagedDataReader & BinaryFileReader documentation (#1968) 2024-10-01 17:07:51 -07:00
SPONSORS.md chore: Updates readme files (#2247) 2025-07-27 11:04:32 -07:00
stylecop.json Updates formatting rules (#199) 2020-08-25 18:00:51 -07:00
THIRD-PARTY-NOTICES chore: Updates 3rd party notices (#1042) 2022-06-01 09:42:11 -07:00
version.json feat: Upgrades networking to use io_uring. (#2315) 2026-02-01 16:02:32 -08:00

ModernUO - Ultima Online Server Emulator for the modern era!

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Ultima Online Server Emulator for the modern era!

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Requirements

Supported Operating Systems

Windows 10/11/2012/2016/2019/2022/2025 MacOS 14+ Debian 12+ Ubuntu 22+ LTS
Alpine 3.22+ Fedora 42+ RedHat 9+ CentOS Stream 9+ openSUSE 15.6+ SUSE Enterprise 15 SP6 Linux Mint 21+ Arch

Required Frameworks

All Operating Systems

.NET

Windows

VC++ Redistributable v14

Development

git .NET

Supported IDEs

Jetbrains Rider 2025.3+ space VSCode space Visual Studio 2026

Getting Started

  • Install prerequisite requirements
  • Clone this repository (or download the latest):
    • git clone https://github.com/modernuo/ModernUO.git
  • Open ModernUO.sln to start developing

Building/Publishing

  • Run ./publish.cmd [release|debug (default: release)] [os] [arch (default: x64)]

Linux Prerequisites

Fedora, CentOS, RHEL, etc

dnf upgrade --refresh -y
# CentOS does not come with EPEL enabled
dnf install -y epel-release epel-next-release
dnf install -y findutils libicu libdeflate-devel zstd libargon2-devel liburing-devel

Ubuntu, Debian, etc

apt-get update -y
apt-get install -y libicu-dev libdeflate-dev zstd libargon2-dev liburing-dev

OSX Requirements

brew install icu4c libdeflate zstd argon2

Running the Server

  • Follow the publish instructions
  • Run ModernUO.exe or dotnet ModernUO.dll from the Distribution directory

Troubleshooting / FAQ

Want to sponsor?

Thank you for supporting us! You can find out how by visiting the sponsors page.

Collaborators

Kamron Batman Mark1145

Thanks

  • RunUO Team & Community
  • Voxpire, the ServUO Team & Community
  • Karasho, Jaedan and the ClassicUO Community



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