aCis Pack Setup: Build and Run an Interlude C6 Server
An aCis pack setup is the most direct route to a retail-like Interlude C6 server you fully control. aCis ("another Crappy interlude server") is a Java emulator built on L2J work and locked to a single chronicle, which is exactly why private server owners keep coming back to it. Its GeoData is reused across other packs, its behaviour tracks retail closely, and the project is tuned for Interlude instead of being stretched across a dozen chronicles. This guide walks a server owner through prerequisites, the Ant build, the database installer, configuration, the hexid handshake, and the client-side patch, including the JDK 21 build trap that stops most first-time setups.
What aCis Is and Why Interlude Admins Pick It
aCis stands for "another Crappy interlude server". It is a Java Lineage 2 server emulator derived from L2J work, and unlike general-purpose projects it targets one chronicle only: Interlude (C6). That narrow focus is the point. Because the codebase never has to serve Kamael, Gracia, or later systems, behaviour stays close to retail Interlude, quests and skills are tuned for that era, and the GeoData that ships with aCis is good enough that other packs reuse it.
The project follows a freemium model. The public sources are free, while the latest and most refined revisions are reserved for supporters who contribute money or code. If you want the newest fixes you either donate or send merge requests. The community forum at acis.i-live.eu is where revisions, changelogs, and support threads live, and the public repository is at gitlab.com/Tryskell/acis_public.
For context, L2JMobius supports many chronicles and is very active, which makes it a strong general choice. aCis is the opposite bet: Interlude only, prized for retail fidelity. If your server is an Interlude C6 project, that trade is usually worth it.
Prerequisites: JDK, MariaDB, Eclipse, and Ant
Four things must be in place before the first build: a JDK, MariaDB, Eclipse (the IDE for Java Developers package), and Ant. On Windows, the MariaDB package ships with HeidiSQL, which is a convenient way to inspect the two databases later. MariaDB itself is a standard install from mariadb.org.
The JDK version is not optional, because it depends on the aCis revision you are building:
| aCis revision | Required JDK |
|---|---|
| Below 381 | JDK 8 |
| 381 to 406 | JDK 11 |
| Above 406 | JDK 21 |
Current public revisions are in the 4xx range, so JDK 21 is the modern choice. Both Liberica JDK 21 and OpenJDK 21 work. The important detail is to point Eclipse and Ant at the same JDK 21 that the sources target. Mixing a newer or older JDK than the revision expects is a common source of confusing build output.
Getting the Source: Public Revisions vs Supporter Builds
Start from the public repository. Clone it into a workspace folder and check the revision number in the readme or changelog so you know which JDK and which feature set you are working with. Because newer revisions are gated behind support, the public tree may lag the bleeding edge, and that is expected rather than a sign of a broken download.
If you maintain a live server and depend on recent fixes, the supporter revisions are the honest upgrade path. Review the forum changelogs before deciding, because some revisions change config keys or database expectations, and you will want to plan a maintenance window rather than patching blind.
Import and Build With Ant (and the JDK 21 Trap)
The project ships a build.xml Ant script. In Eclipse, import the aCis_gameserver project, let it resolve the jars under lib/, then run the Ant build. The output is l2jserver.jar, which belongs in the gameserver libs/ folder. On Ubuntu 22 or 24 there is also a community installer that installs JDK 21, MariaDB, Apache with PHP and Adminer, and Ant, creates the database user and both databases, fills in the installer and config files, builds the pack, and lays everything out. That automation saves a lot of time, though you should still read what it changes.
The build gotcha worth knowing on modern JDKs: on JDK 18 and newer, Apache Ant's use of the Security Manager throws an error that reads UnsupportedOperationException: Setting a Security Manager is not supported. It is not a problem with the aCis code. The clean fix is to use a recent Eclipse and Ant version whose build no longer relies on the deprecated Security Manager. If you are stuck on an older toolchain, you can pass the Ant property -Dant.securitymanager.usage.warn=true to get past it, but updating Eclipse is the tidier solution.
If the build succeeds but the server will not start, the first thing to check is the Eclipse JRE. It must be JDK 21, matching the sources, not a newer JDK your machine happens to prefer.
Install the Databases and Configure the Pack
The database installer is database_installer.sh on Linux or the matching .bat on Windows. It creates and seeds the login database and the game database, which are two separate schemas. Make sure the credentials you enter match the user MariaDB is configured to accept, and run the installer again after a pack update if a revision changes the schema.
All configuration lives in the config/ folder:
server.propertiesfor the game server: rates, ports, and gameplay toggles.loginserver.propertiesfor the login server: account handling and the hexid check.hexid.txt, the file that ties a registered game server to the login server.geoengine.propertiesfor GeoData, pathfinding, and related performance settings.npcs.properties,players.properties,siege.properties,clans.properties, andevents.propertiesfor the rest of the world.
Read each file before changing it. Most startup failures on a first build are a wrong database credential, a wrong port, or a config key that a newer revision renamed.
Register the Hexid, Start Order, and Client Patch
The hexid is generated when you register the game server, and then copied so the login server accepts it. If the login server rejects the game server, the hexid is almost always the culprit: regenerate it, place it where hexid.txt is expected, and confirm both sides agree.
Start order matters. Bring up the login server first, then the game server. Starting the game server before the login server is a reliable way to see connection errors that have nothing to do with your actual configuration.
On the client side you need an Interlude C6 client plus a patched system folder. The classic Interlude client uses protocol 746, so the patch must match that protocol, or the client will fail to connect even when the server is perfectly healthy.
Once the server runs, the practical next step is getting it in front of players. You can list it through /addnews, compare your positioning against the wider directory in /all-servers, and take a stronger placement with /addnews_vip. A working aCis pack is only half the job; a clear listing is what turns it into a populated server.