Phasmophobia

Phasmophobia is a 1–4 player online co-op psychological horror game developed and published by solo developer Kinetic Games, released on Steam Early Access on September 18, 2020. Players take on the role of paranormal investigators tasked with identifying the type of ghost haunting a location using a collection of equipment — EMF readers, spirit boxes, UV torches, and more. Each round takes place on one of several hand-crafted maps, ranging from small houses to large asylums, with over 20 distinct ghost types each exhibiting unique behaviors. The game supports both flat-screen and VR play simultaneously, with full cross-play between VR and non-VR players in the same lobby.

Phasmophobia is built on Unity and uses Photon PUN 2 (Photon Unity Networking) for its multiplayer layer. Photon PUN 2 operates as a relay-based system: all traffic is routed through Photon's globally distributed relay servers rather than directly between players. This is not peer-to-peer — one player acts as the "Master Client" (room host) for game logic authority, but packet transit is always mediated by Photon relay infrastructure. The game uses UDP as its primary transport protocol, defaulting to port range 5055–5058, with an alternative port range of 27000–27002 selectable in game settings. Photon Cloud servers are distributed globally, with nodes in North America, Europe, Asia, and Australia.

Phasmophobia achieved significant cultural impact shortly after launch, reaching an all-time Steam concurrent peak of 112,404 players in October 2020. As of early 2026 the game averages around 13,000 concurrent players with monthly peaks around 30,000, sustained through ongoing Early Access content updates including new ghost types, maps, and the Nightmare mode difficulty overhaul. The game has no traditional anti-cheat system — Kinetic Games relies on custom in-process detection and the cooperative, non-competitive nature of the game to manage cheating, which is a low priority target compared to PvP titles.