If the entire BioShock series has passed you by this generation -- anyone? -- you can now pick up the whole lot for a shade over sevel Quid. The superlative original game still stands tall with its compelling setting and fearsome twist, while 2K Marin's sequel was arguably redundant yet hit hard with a more emotional storyline.
Infinite? I was riveted for the duration, but the more I think about it, the less I like it. Still worth playing, though, so you can wade into debating its ambitious plot and moaning about its rubbish tower defence bit. Thanks to jaystan @ HUKD!