R.E.P.O.

R.E.P.O. is an online co-op horror game developed and published by Swedish indie studio semiwork, released in Early Access on Steam on February 26, 2025. Up to six players take on the role of Semibots — robotic debt collectors tasked by an unseen creator to infiltrate procedurally generated environments, locate valuable physics-based objects, and extract them without being destroyed by hostile creatures. The game emphasizes cooperative chaos: items must be physically handled, thrown, and passed between players, making every extraction a coordination challenge. Voice proximity chat, shared inventory, and permadeath-lite mechanics reinforce the cooperative horror atmosphere. The game launched to overwhelming commercial and critical success, peaking at over 230,000 concurrent players during its first weekend and selling approximately 8.7 million copies in its launch month alone — making it the highest-grossing paid game on Steam for the week of March 11–18, 2025. It was later awarded the Golden Joystick Award for Best Early Access Game in November 2025.

R.E.P.O. is built on Unity and uses Photon Unity Networking (PUN) for its multiplayer infrastructure. Semiwork chose PUN on the recommendation of fellow developers at Landfall, who described it as a reliable and ergonomic framework. Photon provides global cloud relay servers, meaning players do not connect directly to each other — all multiplayer traffic routes through Photon's regional cloud infrastructure. The game uses Photon Voice for in-game proximity voice chat. As of Early Access, the game has no anti-cheat system — a deliberate decision by the developer to preserve mod compatibility, though semiwork has publicly acknowledged the tradeoff and solicited community input on potential future anti-cheat solutions for public matchmaking.

The game's viral success created significant scaling challenges for its small development team. Player feedback from regions outside North America and Europe frequently highlights high latency due to geographic distance from Photon's primary relay infrastructure. Photon PUN supports up to 16 hosting regions globally including Asia, Australia, South America, Japan, South Korea, India, and others — but the specific subset of regions enabled for R.E.P.O. is controlled by the developer's Photon dashboard configuration and was not publicly documented at the time of this profile. The game has an active modding community with tools on Thunderstore, and semiwork has continued updating the game with new content and stability improvements throughout its Early Access period.