diff --git a/lib/fudo/minecraft-clj.nix b/lib/fudo/minecraft-clj.nix
index 309cbec..fb81b5c 100644
--- a/lib/fudo/minecraft-clj.nix
+++ b/lib/fudo/minecraft-clj.nix
@@ -40,21 +40,117 @@ let
     "-Daikars.new.flags=true"
   ];
 
+  worldOpts = { name, ... }:
+    let world-name = name;
+    in {
+      options = with types; {
+        enable = mkEnableOption "Enable this world.";
+
+        world-name = mkOption {
+          type = str;
+          description = "Name of this world.";
+          default = world-name;
+        };
+
+        port = mkOption {
+          type = port;
+          description = "Port on which to run this Minecraft world.";
+          default = 25565;
+        };
+
+        difficulty = mkOption {
+          type = enum [ "peaceful" "easy" "medium" "hard" ];
+          description = "Difficulty setting of this server.";
+          default = "medium";
+        };
+
+        game-mode = mkOption {
+          type = enum [ "survival" "creative" "adventure" "spectator" ];
+          description = "Game mode of the server.";
+          default = "survival";
+        };
+
+        hardcore = mkOption {
+          type = bool;
+          description = "Give players only one life to live.";
+          default = false;
+        };
+
+        world-seed = mkOption {
+          type = nullOr int;
+          description = "Seed to use while generating the world.";
+          default = null;
+        };
+
+        motd = mkOption {
+          type = str;
+          description = "Message with which to greet users.";
+          default = "Welcome to ${world-name}";
+        };
+
+        allow-cheats = mkOption {
+          type = bool;
+          description = "Allow cheats on this server.";
+          default = true;
+        };
+
+        allocated-memory = mkOption {
+          type = int;
+          description = "Memory to allocate to Minecraft, in GB.";
+          default = 4;
+        };
+
+        pvp = mkOption {
+          type = bool;
+          description = "Allow player-vs-player combat.";
+          default = true;
+        };
+      };
+    };
+
+  validChar = c: !isNull (builtins.match "^[a-zA-Z0-9_-]$" c);
+
+  swapSpace = replaceStrings [ " " ] [ "_" ];
+
+  sanitizeName = name:
+    concatStringsSep ""
+    (filter validChar (stringToCharacters (swapSpace name)));
+
+  worldStateDir = worldOpts:
+    "${cfg.state-directory}/${sanitizeName worldOpts.world-name}";
+
+  genProps = worldOpts: {
+    level-name = worldOpts.world-name;
+    level-seed = worldOpts.world-seed;
+    motd = worldOpts.motd;
+    difficulty = worldOpts.difficulty;
+    gamemode = cfg.game-mode;
+    allow-cheats = worldOpts.allowCheats;
+    server-port = worldOpts.port;
+    hardcore = worldOpts.hardcore;
+    pvp = worldOpts.pvp;
+  };
+
+  toProps = attrs:
+    let
+      boolToString = v: if v then "true" else "false";
+      toVal = v: if isBool v then boolToString v else toString v;
+      toProp = k: v: "${k}=${toVal v}";
+    in concatStringsSep "\n" (mapAttrsToList toProp attrs);
+
+  genPropsFile = worldOpts:
+    pkgs.writeText "mc-${sanitizeName worldOpts.world-name}.properties"
+    (toProps (genProps worldOpts));
+
 in {
   options.fudo.minecraft-clj = with types; {
     enable = mkEnableOption "Enable Minecraft server with Clojure repl.";
 
-    data-dir = mkOption {
+    state-directory = mkOption {
       type = str;
       description = "Path at which to store Minecraft data.";
     };
 
-    allocated-memory = mkOption {
-      type = int;
-      description = "Memory to allocate to Minecraft, in GB.";
-      default = 4;
-    };
-
     user = mkOption {
       type = str;
       description = "User as which to run the minecraft server.";
@@ -66,6 +162,18 @@ in {
       description = "Group as which to run the minecraft server.";
       default = "minecraft-clj";
     };
+
+    admins = mkOption {
+      type = listOf str;
+      description = "List of users to treat as administrators.";
+      default = [ ];
+    };
+
+    worlds = mkOption {
+      type = attrsOf (submodule worldOpts);
+      description = "List of worlds to run on this server.";
+      default = { };
+    };
   };
 
   config = mkIf cfg.enable {
@@ -79,35 +187,59 @@ in {
       groups."${cfg.group}" = { members = [ cfg.user ]; };
     };
 
-    systemd.services.minecraft-clj = {
-      description = "Minecraft server with Clojure REPL.";
-      wantedBy = [ "multi-user.target" ];
-      after = [ "network-online.target" ];
-      serviceConfig = {
-        User = cfg.user;
-        Group = cfg.group;
-        ExecStart = let
-          mem = "${toString cfg.allocated-memory}G";
-          memFlags = [ "-Xms${mem}" "-Xmx${mem}" ];
-          flags = commonFlags ++ memFlags
-            ++ (optionals (cfg.allocated-memory >= 12) highMemFlags);
-          flagStr = concatStringsSep " " flags;
-        in "${pkgs.papermc}/bin/minecraft-server ${flagStr}";
+    systemd = {
+      tmpfiles.rules = map (worldOpts:
+        "d ${worldStateDir worldOpts} 0700 ${cfg.user} ${cfg.group} - -")
+        (attrValues cfg.worlds);
 
-        Restart = "always";
-        NoNewPrivileges = true;
-        PrivateTmp = true;
-        PrivateDevices = true;
-        ProtectSystem = "strict";
-        ProtectHome = true;
-        ProtectControlGroups = true;
-        ProtectKernelModules = true;
-        ProtectKernalTunables = true;
-        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" ];
-        RestrictRealtime = true;
-        RestrictNamespaces = true;
-        MemoryDenyWriteExecute = true;
-      };
+      services = mapAttrs' (_: worldOpts:
+        let
+          sanitizedName = sanitizeName worldOpts.world-name;
+          serverName = "minecraft-clj-${sanitizedName}";
+          stateDir = worldStateDir worldOpts;
+          startScript = let
+            admins-file = pkgs.writeText "${sanitizedName}-ops.txt"
+              (concatStringsSep "\n" cfg.admins);
+            props-file = genPropsFile worldOpts;
+
+          in pkgs.writeShellScript "mc-initialize-${sanitizedName}.sh" ''
+            cp -f ${admins-file} ${stateDir}/ops.txt
+            cp -f ${props-file} ${stateDir}/server.properties
+            chmod u+w ${stateDir}/server.properties
+          '';
+
+        in nameValuePair serverName {
+          enable = worldOpts.enable;
+          description =
+            "${worldOpts.world-name} Minecraft Server with Clojure REPL";
+          wantedBy = [ "multi-user.target" ];
+          after = [ "network-online.target" ];
+          serviceConfig = {
+            User = cfg.user;
+            Group = cfg.group;
+            WorkingDirectory = stateDir;
+            ExecStart = let
+              mem = "${toString worldOpts.allocated-memory}G";
+              memFlags = [ "-Xms${mem}" "-Xmx${mem}" ];
+              flags = commonFlags ++ memFlags
+                ++ (optionals (cfg.allocated-memory >= 12) highMemFlags);
+              flagStr = concatStringsSep " " flags;
+            in "${pkgs.papermc}/bin/minecraft-server ${flagStr}";
+
+            Restart = "always";
+            NoNewPrivileges = true;
+            PrivateTmp = true;
+            PrivateDevices = true;
+            ProtectSystem = "strict";
+            ProtectHome = true;
+            ProtectControlGroups = true;
+            ProtectKernelModules = true;
+            ProtectKernalTunables = true;
+            RestrictAddressFamilies = [ "AF_INET" "AF_INET6" ];
+            RestrictRealtime = true;
+            RestrictNamespaces = true;
+          };
+        }) cfg.worlds;
     };
   };
 }