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diff --git a/src/crepe/manager/SystemManager.h b/src/crepe/manager/SystemManager.h
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+#pragma once
+
+#include <memory>
+#include <typeindex>
+#include <unordered_map>
+#include <vector>
+
+#include "../system/System.h"
+
+#include "Manager.h"
+
+namespace crepe {
+
+/**
+ * \brief Collection of all systems
+ *
+ * This manager aggregates all systems and provides utility functions to retrieve references to
+ * and update systems.
+ */
+class SystemManager : public Manager {
+public:
+	SystemManager(Mediator &);
+
+	/**
+	 * \brief Per-frame update.
+	 *
+	 * Updates the game state based on the elapsed time since the last frame.
+	 */
+	void frame_update();
+
+	/**
+	 * \brief Fixed update executed at a fixed rate.
+	 *
+	 * This function updates physics and game logic based on LoopTimer's fixed_delta_time.
+	 */
+	void fixed_update();
+
+private:
+	/**
+	 * \brief Collection of System instances
+	 *
+	 * This map holds System instances indexed by the system's class typeid. It is filled in the
+	 * constructor of \c SystemManager using SystemManager::load_system.
+	 */
+	std::unordered_map<std::type_index, std::unique_ptr<System>> systems;
+	/**
+	 * \brief Collection of System instances
+	 *
+	 * This map holds System instances indexed by the system's class typeid. It is filled in the
+	 * constructor of \c SystemManager using SystemManager::load_system.
+	 */
+	std::vector<std::reference_wrapper<System>> system_order;
+	/**
+	 * \brief Initialize a system
+	 * \tparam T System type (must be derivative of \c System)
+	 */
+	template <class T>
+	void load_system();
+
+public:
+	/**
+	 * \brief Retrieve a reference to ECS system
+	 * \tparam T System type
+	 * \returns Reference to system instance
+	 * \throws std::runtime_error if the System is not initialized
+	 */
+	template <class T>
+	T & get_system();
+
+public:
+	/**
+	 * \brief SystemManager snapshot
+	 *
+	 * The SystemManager snapshot only stores which systems are active
+	 */
+	typedef std::unordered_map<std::type_index, bool> Snapshot;
+	/**
+	 * \brief Save a snapshot of the systems' state
+	 * \returns Copy of each system's active property
+	 */
+	Snapshot save();
+	/**
+	 * \brief Restore system active state from a snapshot
+	 * \param snapshot Snapshot to restore from (as returned by \c save())
+	 */
+	void restore(const Snapshot & snapshot);
+	//! Disable all systems
+	void disable_all();
+};
+
+} // namespace crepe
+
+#include "SystemManager.hpp"