Two of Valves undisputed classics are making their Android debut today, courtesy of Nvidias Shield console: Portal and Half-Life 2. Costing $10 each, the two games were ported by Nvidia, which explains why theyre only playable on the Shield. Still, the job has been done with Valves unreserved blessing and a promise by Doug Lombardi that you \can expect the same gameplay\ as on the original PC versions. With a price cut to $199 and a growing library of games and features, Nvidias efforts at recreating PC-class gaming on an Android portable are looking increasingly compelling.