diff --git a/src/Domain/DeploymentZone.php b/src/Domain/DeploymentZone.php
new file mode 100644
index 0000000..9e2f993
--- /dev/null
+++ b/src/Domain/DeploymentZone.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace BattleForge\Domain;
+
+use InvalidArgumentException;
+
+final readonly class DeploymentZone
+{
+    /** @param list<Position> $positions */
+    public function __construct(
+        public string $teamId,
+        public array $positions,
+    ) {
+        if ($teamId === '') {
+            throw new InvalidArgumentException('Deployment zone team id cannot be empty.');
+        }
+
+        if ($positions === []) {
+            throw new InvalidArgumentException('Deployment zone must contain at least one position.');
+        }
+
+        if (!array_is_list($positions)) { // @phpstan-ignore function.alreadyNarrowedType (Runtime guard: PHPDoc is not a runtime contract for JSON-sourced arrays in Plan 4.)
+            throw new InvalidArgumentException('Deployment zone positions must be a list.');
+        }
+    }
+
+    public function contains(Position $position): bool
+    {
+        foreach ($this->positions as $candidate) {
+            if ($candidate->key() === $position->key()) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}
diff --git a/src/Domain/ObjectiveControl.php b/src/Domain/ObjectiveControl.php
new file mode 100644
index 0000000..99914ff
--- /dev/null
+++ b/src/Domain/ObjectiveControl.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace BattleForge\Domain;
+
+use InvalidArgumentException;
+
+final readonly class ObjectiveControl
+{
+    /** @param array<string, int> $roundsByTeam */
+    public function __construct(public array $roundsByTeam)
+    {
+        foreach ($roundsByTeam as $teamId => $count) {
+            if ($teamId === '') {
+                throw new InvalidArgumentException('Objective control team id cannot be empty.');
+            }
+            if ($count < 0) {
+                throw new InvalidArgumentException('Objective control count cannot be negative.');
+            }
+        }
+    }
+
+    public static function empty(): self
+    {
+        return new self([]);
+    }
+
+    public function recordRound(string $controllerTeamId): self
+    {
+        if ($controllerTeamId === '') {
+            throw new InvalidArgumentException('Controller team id cannot be empty.');
+        }
+
+        $next = $this->roundsByTeam;
+        $next[$controllerTeamId] = ($next[$controllerTeamId] ?? 0) + 1;
+
+        return new self($next);
+    }
+
+    /** @return array{teamId: string, rounds: int} */
+    public function forTeam(string $teamId): array
+    {
+        return ['teamId' => $teamId, 'rounds' => $this->roundsByTeam[$teamId] ?? 0];
+    }
+}
diff --git a/src/Domain/ObjectiveMarker.php b/src/Domain/ObjectiveMarker.php
new file mode 100644
index 0000000..a3d9b23
--- /dev/null
+++ b/src/Domain/ObjectiveMarker.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace BattleForge\Domain;
+
+use InvalidArgumentException;
+
+final readonly class ObjectiveMarker
+{
+    public function __construct(
+        public string $id,
+        public Position $position,
+    ) {
+        if ($id === '') {
+            throw new InvalidArgumentException('Objective id cannot be empty.');
+        }
+    }
+
+    public function key(): string
+    {
+        return $this->id;
+    }
+}
diff --git a/src/Domain/VictoryCondition.php b/src/Domain/VictoryCondition.php
new file mode 100644
index 0000000..8790875
--- /dev/null
+++ b/src/Domain/VictoryCondition.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace BattleForge\Domain;
+
+enum VictoryCondition: string
+{
+    case EliminateAll = 'eliminate_all';
+    case HoldObjective = 'hold_objective';
+}