After some domain links hinting at a new title, the sequel to Metro 2033 has officially been dubbed Metro 2033: Last Light in a THQ investor call.
Many believed the game would be called Metro 2034, as the game will be based off of the book written by Russian author Dmitry Glukhovsky that's called Metro 2034.
Platforms are currently unknown, but Metro 2033 released on the Xbox 360 and PC. It's also stated that 4A Games are planning to release the game at some point next year.
Source: Game Informer