OnLive

OnLive describes itself as a games on demand service. A simple explanation how the service works is, it takes the input from your gaming controller, but instead of sending it to your gaming machine on which the game is processed, this input is sent via the internet to a server in an OnLive data center which is processing this input and calculating the next frame of the game to be displayed. That frame is then encoded with a proprietary OnLive encoder chip and sent back to your screen as fast as possible. OnLive uses the UDP internet protocol to ensure speedy communication between you and their servers. They've also made contracts with mayor ISPs to ensure a quality connection for their users.

As of now you can use OnLive on the PC, the Mac and the TV via the OnLive Game System which OnLive also calls the MicroConsole. The system requirements for OnLive on the PC or Mac are:
MINIMUM SYSTEM REQUIREMENTS:

Internet Connection: 3 Mbps wired or Wi-Fi connection

Operating System: Windows 7 or Vista (32 or 64-bit) or XP SP3 (32-bit), Mac OS X 10.5.8 or later

Computer: Most PCs and netbooks, all Intel-based Macs

Screen Resolution: 1024x576

RECOMMENDED SYSTEM REQUIREMENTS:

Internet Connection: 5 Mbps wired or Wi-Fi connection

Operating System: Windows® 7 or Vista (32 or 64-bit) or XP SP3 (32-bit)

Mac® OS X 10.6 or later

Computer: Dual-core PCs, all Intel-based Macs

Screen Resolution: 1280x720

On the PC side you should have at least a dual core processor and a graphics card with 256 MB that supports Pixel Shader 2.0.
The OnLive Game System requires:

1. Wired broadband connection near your television (3 Mbps minimum required, 5+ Mbps recommended)
2. HDTV with an HDMI connector OR a Component Cable Adapter available from the OnLive Web Store

As written OnLive currently works in 720p, but 1080p is already worked on and in closed beta testing. The games usually run with 60 fps.

Some of the features of the service are the arena where you can spectate other players who have it enabled and voice chat with them, brag clips is a feature which records the last ten seconds of your gameplay, a profile with a friends list and text chat capability, the game marketplace, showcase section and the OnLive settings.

OnLive runs PC versions of games on their servers and all of their games support mouse and keyboard input. Many of the games support XInput controllers like the official Xbox 360 gamepad. Here's a list of supported controllers:

OnLive Wireless Controller (OnLive Game System only)

Microsoft® Xbox 360® Controller for Windows

Microsoft Xbox 360 Wireless Controller for Windows (requires the Microsoft Wireless Gaming Receiver)

Logitech® ChillStream™

Logitech® F510

Saitek® P3200 Rumble Pad

Mad Catz® GamePad

OnLive also sells their own wireless controller, but it's currently only usable with the MicroConsole.

OnLive was unveiled at the GDC 2009 conference. After that they were running an open beta period starting september of 2009 till their launch. OnLive officially launched on June 17th 2010, just after their presentation at E3 2010, with 17 games. Their launch was notable for the fact that EA pulled all their games from OnLive just prior launch and their relationship is still troubled. OnLive is currently only available in the USA and Canada, but you can use it from many countries around the world. They plan to launch their service in the UK this autumn and then branch on into Europe and Asia. They are partnered with major game publishers and technology partners. Notable investors in the company are AT&T, Warner Bros., Autodesk, Maverick Capital, BT and HTC.

OnLive currently has more than 100 games available. Among those are games like Homefront, Duke Nukem Forever, Borderlands, Red Faction Armageddon, Batman Arkham Asylum and Just Cause 2. Many of their games are available through the OnLive PlayPack. The PlayPack is a Netflix like all-you-can-eat monthly flat-rate plan, which costs $9.99/month and includes a growing library of 60+ slightly older games. More and more publishers are releasing their games on OnLive day-and-date, with the notable absence of EA and Activision. The purchasing options for OnLive include the aforementioned PlayPack and what OnLive calls a PlayPass. With the PlayPass you are basically buying game time, you can rent games for 3 or 5 days with the prices ranging from $5 to $7, or you can buy a full PlayPass which is basically buying a game and also has comparable prices to retail games. You can also demo all games except Homefront mostly for 30 minutes and you can restart the demos as much as you like. Trials of games can also be launched directly with a link from web pages. OnLive also runs many promotional deals like Steam, where they lower the price of the games. They also have pre-order deals where the game is discounted, you get another free PlayPass or get the MicroConsole for free.

Among the games coming to OnLive are Deus Ex Human Revolution, Warhammer 40k Space Marine, Batman Arkham City, Fear 3, From Dust, Dead Island, Dungeon Siege 3, Dirt 3, Call of Juarez The Cartel and The Witcher 2 Assassins of Kings.

Since the release the OnLive service has constantly evolved with additions like latency reduction, better picture quality, performance increases, achievements, voice chat, Facebook integration, friends invite, etc. They also have great plans for the future like games displaying in 1080p resolution, games displayed in 3D, integration into Vizio TVs, Blu-Ray players and Tablets, integration into cable boxes. In the autumn they plan to release their client for iOS and Android devices. They're making overlay touch controls for touch devices which will be usable in some games, Ubisoft's From Dust is getting exclusive touch controls for OnLive, and they will introduce the Universal OnLive Wireless Controller which can be used with PCs, Macs, TVs, Blu-Ray players, cable boxes, Google TV, tablets, smartphones, etc.

Anyone can signup for the OnLive game service and see how it works on their connection.