Google unveiled its new mobile operative system Android 4.4 KitKat during a Halloween event in San Francisco while also announced its long-awaited new Nexus 5 smartphone.

KitKat is a simpler and cleaner version of Android that still looking a lot like Jelly Bean and a new effort from Google to make cheaper Android devices and prepare the world for wearable computing.

"KitKat has a better memory management that allows entry-level devices to run with only 512 Mb of RAM," Amir Efrati, former Wall Street Journal reporter, said. "It has support for three new sensors including a step detector, step counter and a geomagnetic rotation vector that could help making future Google smartwatches useful for fitness tracking."

KitKat, available now only for Nexus 5, has a new voice recognition engine that allows Voice Search to go hands-free as well for Google Now features, that lets the user interact with the phone by only saying "OK Google" without even touching the phone screen.

The Nexus 5 is manufactured by LG in a variety of bands in order to work internationally and without any contract, though Verizon's band isn't supported yet.

The 4G/LTE phone has a 5-inch screen, is thinner and lighter than its previous generation with a Snapdragon 800 2.3GHz processor, Corning Gorilla Glass 3, wireless charging capability, an HDR 8 Megapixels rear facing camera with Optical Image Stabilization and a 1.3 Megapixels front facing camera, a 2300 mAh for a talk time up to 17 hours and a stanby time up to 300 hours.

Nexus 5 has option for a 16Gb or 32Gb internal storage, 2Gb in RAM and is available online today in 10 countries and retail stores starting at $349 without a contract.