Photon

Photon is a family of multiplayer networking SDKs and a managed cloud for running game sessions, developed by Exit Games of Hamburg and sold under the Photon Engine brand. It is a networking layer, not a full game backend: Photon synchronises game state between players and provides rooms, matchmaking, voice and chat, while accounts, economies and LiveOps normally come from a separate gaming backend. Exit Games was founded in 2003 (PocketGamer.biz, December 2024).

Fusion: state synchronisation

Photon Fusion is the current general-purpose product for real-time multiplayer networking. On Unity, Fusion 2 supports three topologies. In Shared Mode, clients connect to Photon Cloud, which holds session state; Photon recommends it for co-op, social, mobile, WebGL and VR games and is frank that it offers limited competitive integrity. In Host Mode one player is the authoritative host, which is cheaper than servers but lets the host manipulate state. In Server Mode a headless dedicated server holds authority, which Photon calls the strongest topology for competitive and cheat-sensitive games and which requires the studio to operate servers.

The Unity package is actively maintained: the Unity Asset Store listing showed Fusion 2.1.3, released September 22, 2026.

Quantum: deterministic simulation

Photon Quantum takes a different approach. It is a deterministic game engine layered on Unity, built on an entity component system, in which every client runs the same simulation from the same inputs. Clients advance the simulation locally using input prediction, and a rollback system corrects mispredictions. Photon positions it for fighting games, RTS, MOBA, sports and .io titles, where input-level synchronisation, replays and fairness under high latency matter more than ease of adoption. Quantum first launched in 2017 and Quantum 3 became a Unity Verified Solution in September 2024, according to Photon's blog. It requires deterministic programming patterns and is Unity-focused.

Realtime, PUN and the rest of the family

Photon Realtime is the lower-level rooms and matchmaking API that sits beneath most Photon products; it leaves state synchronisation to the developer and is the option for turn-based, asynchronous or custom-engine projects, with client libraries in C#, C++, JavaScript and other languages. PUN 2 (Photon Unity Networking), the product many Unity developers learned multiplayer on, is in long-term support: Photon's own guidance is that new Unity projects should use Fusion or Quantum, and that the older Photon Bolt is discontinued. PUN 2 still receives maintenance releases (version 2.56 on the Asset Store, dated September 10, 2026). Photon Voice and Photon Chat cover in-game voice and text, and Photon Server v5 is the self-hosted option for teams with compliance or data-residency requirements.

Engines supported

Photon's support is deepest on Unity. As summarised in the company's machine-readable product overview (dated July 2026):

The practical reading is that a Unity studio can use any Photon product today, while Unreal Engine and Godot teams are adopting a newer line that Photon itself flags as still maturing.

Pricing, scale and fit

Photon prices by concurrent users (CCU) rather than monthly players. Fusion and Quantum include 100 CCU free; PUN, Realtime, Chat and Voice include 20 CCU free. Photon's own forecasting rule of thumb is that 1 CCU corresponds to about 20 daily or 400 monthly active users. The company states that games on Photon reach more than 1.4 billion monthly active users across over 10,000 launched titles, naming Rec Room, Gorilla Tag, Among Us VR and VRChat; those are vendor-reported figures.

Photon is the right kind of tool when the missing piece is netcode. It is the wrong kind of tool when the missing piece is player data, commerce or live operations, and Photon says as much, listing among the things it is not "a replacement for server-side validation or anti-cheat design". Studios therefore pair it with a backend such as PlayFab, Nakama or Beamable, and, for Server Mode, with a dedicated server host of the kind covered in Unity Multiplay Alternatives.