Head over to the PlayStation Mobile tab on PSN and the first games of the year are out for your Vita. Looking the best bet is Tiki Rush, Escape from Lava Island for £2.19 offering side-scrolling endless running with a 16-bit flavour and only 91MB.
Tiki Rush: Escape From Lava Island from Mercury Active on Vimeo.
Also new is Fleet Connection, an Asian developed about planetary bombardment, on the plus side its free so give it a shot. Also free are Bike Rider DX (57MB) and Rock Boshers DX (39MB, and wins an extra point for its Spectrum loading screens) as part of the still running PSM offers.