These games really intrigue with the apparently survival feeling with (not sure if true) stealth, and obviously I'll start with 2033. But, besides the visuals, what are the main differences between vanilla 2033 and the Redux version? I think I've read something about having changed something (apparently for the better) about the gameplay.
Taken from the DF interview.
Digital Foundry: Metro Redux isn't just a port, it's been improved. How did you choose which improvements to make and did the design of the consoles have anything to do with those choices?
Oles Shishkovstov: Since Metro Last Light hit the shelves we've collected numerous improvement suggestions from our players in order to include them in Metro Redux. The power of the new consoles also allowed us to improve the games in the field most critical to gameplay, especially gunplay and general feel - for example combat and cut-scenes became smoother, and controls became much more responsive. Besides that, the new incarnation of Metro 2033 enjoys a lot of the upgrades introduced in Metro: Last Light: new weapons and their upgrades, improved stealth mode viability and takedowns, improved AI with its more realistic behaviour, and the improved visuals etc..