CCU (Concurrent Users)
CCU — or concurrent users — is the number of players actively connected to a game at the same moment. It is the primary metric studios use to size their server infrastructure, plan capacity, and measure live service health.
CCU vs DAU vs MAU
CCU is often confused with daily active users (DAU) or monthly active users (MAU), but they measure different things. DAU counts how many unique players logged in on a given day; MAU counts unique players in a month. CCU measures how many of those players are connected at the same time. A game with 500,000 DAU might have a peak CCU of 40,000 — the busiest hour of the day when the most players overlap. Infrastructure is sized for peak CCU, not total player count.
Why peak CCU drives your server costs
Every concurrent player needs a server instance. At peak CCU, your fleet must be large enough to run all active sessions simultaneously — so a sudden spike, a free weekend, or a viral moment can double your requirement overnight. Platforms that meter by the hour charge you for every server running during that peak window. Platforms priced on reserved capacity let you model cost directly against your expected CCU ceiling, with no per-session surprises.
CCU and launch spikes
Launch day is the hardest CCU problem in multiplayer games. Peak CCU at launch routinely exceeds pre-launch estimates — sometimes by 2× or more within the first 30 minutes. Servers that take minutes to provision cannot absorb a spike; they queue players or drop connections. Chivalry 2 hit 250,000 concurrent players in its first 30 minutes on Gameye — absorbed in real time because new server instances started in under a second as CCU rose.
See also: How Gameye handles session scaling · Server Fleet · Auto Scaling