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Cloud gaming, sometimes called gaming on demand, is a type of online gaming. Currently there are two main types of cloud gaming: cloud gaming based on video streaming and cloud gaming based on file streaming. Cloud gaming aims to provide end users friction-less and direct play-ability of games across various devices.
Types of cloud gaming
Cloud gaming is an umbrella term used to describe a form of online game distribution. The most common methods of cloud gaming currently are video (or pixel) streaming and file streaming.
"Cloud gaming", also called "gaming on demand", is a type of online gaming that allows direct and on-demand streaming of games onto computers, consoles and mobile devices, similar to video on demand, through the use of a thin client, in which the actual game is stored on the operator's or game company's server and is streamed directly to computers accessing the server through the client. This allows access to games without the need of a console and largely makes the capability of the user's computer unimportant, as the server is the system that is running the processing needs. The controls and button presses from the user are transmitted directly to the server, where they are recorded, and the server then sends back the game's response to the input controls.
Gaming on demand is a game service which takes advantage of a broadband connection, large server clusters, encryption and compression to stream game content to a subscriber's device. Users can play games without downloading or installing the actual game. Game content isn't stored on the user's hard drive and game code execution occurs primarily at the server cluster, so the subscriber can use a less powerful computer to play the game than the game would normally require, since the server does all performance-intensive operations usually done by the end user's computer. Most cloud gaming platforms are closed and proprietary; the first open source cloud gaming platform was not released until April, 2013. 
Cloud gaming based on file streaming, also known as progressive downloading, deploys a thin client in which the actual game is run on the user's gaming device such as a mobile device, a PC or a console. A small part of a game, usually less than 5% of the total game size, is downloaded initially so that the gamer can start playing quickly. The remaining game content is downloaded to the end user's device while playing. This allows instant access to games with low bandwidth Internet connections without lag. The cloud is used for providing a scalable way of streaming the game content and big data analysis.
Cloud gaming based on file streaming requires a device that has the hardware capabilities to operate the game. Often, downloaded game content is stored on the end user's device where it is cached.
Companies that use this type of cloud gaming include Kalydo, Approxy and SpawnApps.
Cloud gaming providers
Active cloud gaming providers
- Gaikai (subsidiary of Sony Computer Entertainment)
- Playcast Media Systems
Video game developer Crytek began research on a cloud gaming system in 2005 for their game Crysis, but halted development in 2007 to wait until the infrastructure and cable Internet providers were up for the task.
On March 10, 2010, OnLive officially launched. The OnLive Game Service then turned on in the US on June 17, 2010, at an initial monthly service fee of $4.95, plus the cost of games and the OnLive microconsole. However, this fee was not to be applied for a year while OnLive worked out their business model and anyone who signed up during 2010 would not be charged until 2011 as well as have their account marked as a "founding member". Later, the fee was removed altogether as part of a review of this business model and as of October 2010, there are no plans to reintroduce this fee to simply use the service.
On February 27, 2011, Gaikai, which allows game publishers and others to embed free streaming gameplay trials on their web sites, launched its open beta with games from Electronic Arts including Dead Space 2, Mass Effect 2, and Sims 3. Gaikai-enabled games can be embedded directly inside websites, on Facebook, or on mobile devices and IPTVs. In spring 2011, Gaikai went live with multiple partnerships including Walmart and The Escapist, as well as announcing deals with Eurogamer and Capcom. Gaikai-enabled games stream from within web browsers without requiring downloads, special plug-ins, or registration, and can be activated by clicking on an enabled advertisement or visiting a Gaikai-powered game destination.
On April 28, 2011, Free, a French Internet service provider, launched "GameTree TV", a gaming on demand platform for the Freebox Revolution, its advanced IPTV set-top-box. The service is based on the GameTree TV platform by TransGaming Inc.
On September 8, 2011, Ubitus, a Taiwanese cloud computing company, launched G CLOUD service based on its product GameCloud, on NTT docomo LTE commercial network with NHN Japan collaboration. It was the world’s first commercial cloud gaming service on LTE network. It was also the world's first commercial cloud gaming service offering MMO and support in-app billing that integrates directly with telecommunication’s payment option. The service covered NTT docomo's Android tablets and smartphone devices.
In August 2012, Square Enix launched their Core Online games service, which offers free and advertising-supported access to some games from their catalog via a web browser. As of February 2013, there are four games available through the service: Hitman: Blood Money, Lara Croft and the Guardian of Light, Mini Ninjas and Tomb Raider: Underworld.
September 11, 2012 saw the launch of CiiNOW, a new cloud gaming platform. CiiNOW claims to have pioneered a new approach called hybrid streaming. Hybrid streaming consists of streaming graphics primitives as well as video simultaneously. It utilizes some processing on a client to achieve better quality at lower bandwidth.
February 20, 2013, during the PlayStation 4 announcement, Sony revealed that it will use its new acquisition of Gaikai to power cloud gaming services for the PlayStation 4, with the eventual goal of making the entire PlayStation catalog available to stream.
On April 17, 2013 the first open source cloud gaming system, GamingAnywhere, was released. GamingAnywhere allows researchers to test their new ideas on a real testbed, service providers to build their services on top of it, and end users to set up game servers using their home workstations (and play anywhere, anytime).
At the Electronic Entertainment Expo in 2013, Sony announced that PlayStation’s cloud gaming services will be available in the United States in 2014. The service will be powered by Gaikai and stream PlayStation 3 titles to owners of PlayStation 4, PlayStation 3, and PlayStation Vita.
In September 2013, a research paper  presents a suite of measurement techniques to quantify the Quality of Service of cloud gaming systems. Conducting such measurements is not an easy task, because most commercial cloud gaming systems are closed and proprietary. Therefore, it is not possible to instrument the cloud gaming systems or install profiling tools on the servers/clients. The proposed measurement techniques are general and can be applied to any cloud gaming systems, so that researchers, users, and service providers may systematically quantify the Quality of Service of these systems.
- 2002: Phantom Entertainment announces cloud gaming console.
- 2004: G-cluster launches the first deployment of cloud gaming in Japan 
- 2005: G-cluster launches the first commercial live deployment of cloud gaming in Europe 
- 2008: The first HD 720p service showcased by G-cluster on Amino STB.
- 2009: OnLive and Gaikai announce cloud based gaming services.
- 2010: Playcast Media Systems launches commercial cloud gaming on demand service with Portugal Telecom in Portugal.
- 2010: SFR launches cloud gaming on demand service on IPTV commercially in France.
- 2010: OnLive launches.
- 2011: Ubitus GameCloud launches cloud gaming service, G CLOUD, on docomo LTE commercially with NHN Japan .
- 2011: Gaikai launches.
- 2011: CloudUnion launches.
- 2012: itsmy launches mobile cloud gaming.
- 2012: Big Fish Games launches Big Fish Unlimited, a cloud gaming service with 100+ games streaming instantly to personal computers, mobile device and internet connected TVs.
- 2012: LG-U+ and Ubitus launched C-games cloud gaming service in South Korea.
- 2012: Ubitus Launched the GameNow Cloud Gaming Service in the US with Verizon Wireless 4G LTE Customers Having First Access. 
- 2012: Square Enix launches their CoreOnline streaming games service for web browsers.
- 2012: CiiNOW launched as a cloud gaming service for Windows, Mac OS X, Linux, Android, and a set-top box.
- 2012: Orange France launches cloud gaming service on IPTV powered by G-cluster technology
- 2012: Big Fish Games launches cloud gaming timeline infographic.
- 2013: Ubitus launches cloud gaming service on Google TV.
- 2013: Ubitus and one2free bring the first LTE cloud gaming service to Hong Kong.
- 2013: GamingAnywhere, the first open source cloud gaming system is released.
- 2013: Dragon Quest X Comes to NTT Docomo's dGame Using Ubitus Mobile Cloud Gaming Technology. 
- 2013: LG Uplus Teams Up with Ubitus to Launch Winning Eleven 2014 over the Cloud. 
- 2013: Sony announces that it will launch a cloud gaming service powered by Gaikai on PlayStation 4 and PlayStation 3 in 2014.
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