diff --git a/models/__init__.py b/models/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/models/errors.py b/models/errors.py
new file mode 100644
index 0000000..e8d99f5
--- /dev/null
+++ b/models/errors.py
@@ -0,0 +1,15 @@
+from dataclasses import dataclass, field
+
+
+@dataclass
+class ValidationError:
+    """Model for validation errors."""
+    loc: list
+    msg: str
+    type: str
+
+
+@dataclass
+class HTTPValidationError:
+    """Model for HTTP validation errors."""
+    detail: list[ValidationError] = field(default_factory=list)
diff --git a/models/requests.py b/models/requests.py
new file mode 100644
index 0000000..3bfebab
--- /dev/null
+++ b/models/requests.py
@@ -0,0 +1,17 @@
+from dataclasses import dataclass
+from typing import Literal
+from uuid import UUID
+
+
+@dataclass
+class GameStartRequest:
+    """Request model for starting a new game."""
+    player_name: str
+
+
+@dataclass
+class GameDecisionRequest:
+    """Request model for making a game decision."""
+    decision: Literal["Accept", "Reject"]
+    session_id: UUID
+    client_id: UUID
diff --git a/models/responses.py b/models/responses.py
new file mode 100644
index 0000000..1a4bfec
--- /dev/null
+++ b/models/responses.py
@@ -0,0 +1,23 @@
+from dataclasses import dataclass
+from typing import Dict, Optional, Any
+from uuid import UUID
+
+
+@dataclass
+class GameStartResponse:
+    """Response model for a new game started."""
+    message: str
+    session_id: UUID
+    player_id: str
+    client_id: UUID
+    client_data: Dict[str, Any]
+    score: int
+
+
+@dataclass
+class GameDecisionResponse:
+    """Response model for a game decision result."""
+    status: str
+    score: int
+    client_id: Optional[UUID] = None
+    client_data: Optional[Dict[str, Any]] = None