Glossary of terms


A2S is a popular UDP-based game server query protocol that Valve Software keeps as a part of the Steam SDK.

access key

An access key is a unique identifier that points to your account. It’s tied to a secret key. Refer to Authentication.


Allocating is the process of a matchmaker allocating a game server for a game session.

allocated game server

Refer to allocated server.

allocated server

An allocated server is a server that's in use by an allocation. Allocated servers have a populated allocatedID field in their server.json file.

allocated server capacity

Allocated server capacity is the number of allocated game servers within a fleet or fleet region. Game Server Hosting keeps a buffer between the total server capacity and the allocated server capacity to allow the fleet or fleet region to accommodate sudden spikes in allocated servers.

allocated ID

Refer to allocation ID.


An allocation is a request for the best possible game server for a game match. Refer to Allocations.

allocation ID

An allocation ID is an identifier that you (or a matchmaker) assign to an allocation upon creation.

allocation spread

Allocation spread is the maximum number of machines that the reactive scaling system spreads allocations across machines in a fleet or fleet region.

allocation timeout

The allocation timeout is a value that determines the amount of time that the reactive scaling system waits before force-deallocating allocated game servers, even if players are on the server. This value serves as a hard limit on the amount of time that an allocation can exist.

available game server

An available game server is a game server that's ready for a matchmaker to use to fulfill an allocation. Refer to Available servers.

available server

An available server is a server that's ready for a matchmaker to use to fulfill an allocation.

available server pool

The available server pool is a group of game servers in a fleet that's online and ready to fulfill an allocation request.

best available server

The best available server is an available game server that best meets the requirements for an allocation request.


A server buffer is a collection of servers kept in an available state, ready to fulfill an allocation. Refer to Availability buffer.


A build has the files necessary to run your game or application on a server. Refer to Builds.

build configuration

A build configuration manages how a build runs by dictating the query protocol, the application executable path, the configuration variables, and the launch parameters. Refer to Build configurations.

build executable

A build executable is the executable file within a build.

build executable path

The build executable path is the file system location of the build executable. It's relative to the structure of the build files you upload.

build ID

A number that identifies a specific build within the current Unity project.

build install

A build install is a job triggered when you roll out a new build release to the servers in your fleet. Refer to Install lifecycle.

build machine

A dedicated machine for deploying and testing configuration changes, game images, and game image updates. Scaling configurations and fleet settings don't apply to build machines because they exist outside of any fleet. You receive your build machine’s hostname, IP address, and machine ID during the proof-of-concept onboarding stage.

build process

A build process is the process running on a server after launching a build executable.


Capacity refers to the number of game servers within a fleet (game server capacity) or the number of machines within a fleet (machine capacity).

concurrent users

Concurrently connected users (CCU) is the number of players simultaneously connected to a fleet, region, or server at a time.

concurrently connected users

Refer to concurrent users.

configuration variable

A configuration variable is a variable you define on a build configuration. Game Server Hosting passes these variables to servers using the build configuration. Refer to Configuration variables.

container build

A containerized version of a build that lives on the Game Server Hosting container registry. Refer to Container builds.

container registry

The Game Server Hosting container registry is a custom registry for hosting containerized builds.

CPU core count

The CPU core count defines how many CPU cores each server has access to.

CPU frequency

The CPU frequency defines the amount of CPU frequency in megahertz (MHz) each server instance has access to.


Credentials allow you to authenticate with Multiplay's API. Each account has an access key and a secret key that make up the credentials.


Deallocating is the process of removing an allocation.

disabled machine

A disabled machine is a machine that you can't use to fulfill allocations or reservations.


Draining is the process of players leaving a game server after a game session ends.

excess game servers

Refer to excess servers.

excess servers

Excess servers refers to any running game server over the target buffer.


A fleet is a collection of servers that host a game or application in specific regions. Accounts can have one or more fleets, each with its own regions, builds, build configurations, and settings. Refer to Fleets.

force deallocating

Refer to force-deallocate.


Force deallocating is the process of deallocating a game server regardless of the state of the game session.

forced rollout

A forced rollout is a less graceful method of deploying a build update where you force servers to update even if there are players connected. If players are connected when you start a forced rollout, Game Server Hosting kicks the players from the server.

game client

A game client is software that an end-user, or player, interacts with to join a match on a game server.

game map

Game map is a broad term that refers to a playable set of content for a game. The content can be anything from a level to a play area for a game session.

game mode

A game mode is a variation of a game with some configuration altered, such as the number of players allowed per session, the game objective, or the points system.

game session

A game session is a temporary match that players can join to play a game together.

game server

A game server is an instance of a game running on a machine that players can connect to. Each game server instance has a unique server ID, a unique port, a server ID directory, a log file, and a server.json file. Refer to Servers.

game server instance

Refer to game server.

game server query protocol

A game server query protocol is a protocol that facilitates querying information from a game server instance. Game Server Hosting uses the information supplied by the game server query protocol to detect unresponsive game servers and to create live dashboards of advanced analytic data. Refer to Query protocols.

game server slot

A game server slot is a reserved percentage of machine resources on which a game server can run.

game server usages

Game server usages is the average resource consumption per game server, including CPU power, network bandwidth, and memory. Refer to Server density.

game session,game match

A session of multiple players connected to the same game server to play a game together.

game title

A game title is the name of a specific game.

game version

A specific release version of an image of a game server binary.

hardware specifications

Refer to machine specifications.

launch parameter

A launch parameter is a variable sent to a build process as a startup flag when launching the executable on a server. Refer to Launch parameters.

local mirror

Refer to local mirror machine.

local mirror machine

A machine in Multiplay's mirror network that hosts game images for the fleet machines in the same location.


Refer to region.

locked game server

A game server that's disabled for maintenance. You can't use a locked game server to fulfill an allocation or reservation. Refer to Server statuses.


A machine is a physical or virtual computer with a set amount of compute resources that runs servers.

machine capacity

Server density is the number of servers a single machine can fit. The usage settings of the current build configuration determines this number.

machine specifications

Machine specifications include a set of hardware requirements for fleet machines. The requirements might include a minimum processor clock speed, a minimum amount of RAM, and processor configuration options. The machine specifications might vary between bare-metal and cloud machines.

machine state

The state of a machine. A machine can be offline, online and allocated (or reserved), online and available, or online and disabled.


A multiplayer networking feature in games that groups players into a game session.


The process of grouping players together into a game session.

maximum servers

The maximum servers scaling setting controls the maximum number of servers that can run in a region at a time.


The memory defines the amount of RAM (random access memory) in megabytes (MB) each server has access to.

minimum available servers

The minimum available servers scaling setting controls the minimum number of servers that are available in a region at a time. Refer to Scaling settings.

minimum servers

The absolute minimum number of game servers that the reactive scaling system keeps in a fleet or fleet region at any time. Refer to Scaling settings.

minimum standby servers

The number of game servers within a fleet or fleet region that are offline. Standby game servers serve as a form of warm capacity that Game Server Hosting can use to host game servers in case of a sharp influx in currently connected users (CCU).

next available server

A game server from the available server pool that best fits the allocation requirements.

offline game server

A game server that Game Server Hosting has shut down in response to a decrease in the number of total concurrently connected players.

offline server

Refer to offline game server.

online game server

An online game server is a game server that's running and accessible to players on a remote game client.

online server

Refer to online game server.


An individual connected to a game client that has the intention to connect to a game server to join a game session.

player density

Player density is the number of players within a region at a given time.

players per session

Players per session is the maximum number of players that can join a game session.


The process of running a game session on a game server to test a game build, gather feedback from users participating in the playtest, or collect data about the resources the game server uses while hosting a game session. Game Server Hosting uses playtests to calculate game server resource usages to find the optimal server density for the game build.

progressive rollout

A progressive rollout is a graceful method of deploying a build update where you update servers only when they're empty. If there are any players connected to a server, Game Server Hosting waits for your matchmaker to deallocate the server.

proxy payload

The proxy payload is a locally available proxy on game server machines at port 8086 that you can use to retrieve payloads uploaded with the Allocate V2 endpoint


An acronym for quality of service. In the context of Multiplay, it describes the network connection quality between a game server and a game client.

QoS machine

A machine in a specific location that game clients use to retrieve quality of service information. The game client then uses the quality of service information—along with the quality of service information from other QoS servers—to find the best location to join a game session.

QoS service

The QoS service allows game clients to gather quality of service (QoS) data to supply to a matchmaker.


QStat is an open-source command-line tool that interacts with game server query protocols to gather statistics about game servers.

query protocol

A query protocol is a protocol that facilitates querying information from a game server instance. All builds must support a query protocol.

reactive scaling system

The reactive scaling system is a system that allows fleets to respond dynamically to player demand by scaling the number of game servers in a region.


A region is a geographic locations in which a fleet can host servers. Each fleet can have access to one or more regions and each region within a fleet has independent scaling settings. Refer to Regions.


A release is a version of your build that’s ready to release to servers to run your game.


The process of "rolling out" an updated build to all the server in a fleet or fleet region.

rollout mode

A rollout mode is a mode where you deploy a build update. There are two rollout modes: progressive and forced.


Scaling is the process of adjusting the number of servers in a region in response to demand. Refer to Scaling.

scaling down

Scaling down is the process of shutting down and eventually deleting server capacity in response to decreases in allocated servers. Refer to Scaling.

scaling settings

Scaling settings allow you to manage how your fleet scales per region. There are two scaling settings available per region: the minimum available servers and the maximum servers. Refer to Scaling settings.

scaling up

Scaling up is the process of creating more server capacity within a fleet or a fleet region in response to increases in allocated servers. Refer to Scaling.

secret key

A secret key is akin to a password and is only visible when you first generate your credentials. You use the secret key along with the corresponding access key to authenticate with the Game Server Hosting API. Refer to Authentication.


A server, also known as a game server, is an instance of a build executable running on a machine within a fleet. Refer to Servers

server action

A server action is an action (such as start, stop, allocate, and unallocate) performed on a server. Game Server Hosting can perform these actions automatically or you can perform them manually.

server buffer

Refer to buffer.

server density

Refer to machine capacity.

server event

A server event is an event that occurred on a server, such as a server action, failure, or build update. Refer to Server analytics.

server failure

A server failure happens when a server crashes, fails to start, or becomes unreachable. Refer to Server analytics.

server ID directory

Each server instance has a directory on the host machine that has data specific to the server instance. The directory name matches the server's ID.

server log

A server log is an application-level log produced by a build executable. Refer to Server files.

server file

A server file is an application-level file produced by a build executable. Refer to Server files.

server query protocol

Refer to SQP.

server usage

Server usage is the analytic information about the compute resources a server uses.


The server.json file has variable data, such as the current allocation ID, for each server instance. It’s automatically generated and populated for each server. Refer to Server.json file.

shutdown TTL

The shutdown TTL determines the amount of time that the reactive scaling system waits before shutting down a cloud machine with no allocated game server instances. Refer to Scaling settings.


SQP is a query protocol that allows you to retrieve information about a running game server.

standby game server

A game server that exists on a machine that's in a shutdown state. The reactive scaler doesn't include such game servers in the available server pool.

startup parameter

Refer to launch parameter.

target buffer

The number of game servers that a fleet or fleet region should have online and available for new players to join at any time.

total server capacity

The total number of game servers within a fleet or a fleet region.

transient state

A transient state is any machine state that's transitionary, such as when a machine is booting up or shutting down.

unallocated game server

A game server that's available to fulfill an allocation request.

unallocated server

An unallocated server is a server that's not in use by an active allocation. The allocatedID field in its server.json file should be an empty string.

unresponsive game server

A game server that has repeatedly failed to respond to the implemented game server query protocol.