Here is the full list of all 49 Metro: Last Light Redux achievements. It takes around 30-35 hours to unlock all of the achievements on Windows.
Save D6.
Complete the game in Survival Mode.
Remove your mask when Lesnitsky demands it.
Kill the Watchmen attacking the Railcar without taking any damage.
Complete the REVOLUTION level without killing and raising an alarm.
Complete the SEPARATION level without killing or raising alarm.
Complete the BRIDGE level without a kill.
Complete the KSHATRIYA level.
Complete the HEAVY SQUAD level.
Complete the SNIPER TEAM level.
Complete the TOWER level.
Complete the SPIDER LAIR level.
Complete the PAVEL level.
Complete the KHAN level.
Complete the ANNA level.
Spend 1 hour on the DEVELOPER level.
Destroy D6.
Complete the game in Spartan Mode.
Complete all 43 of Artyom's hidden Diary pages.
Make Moskvin tell the truth with help from the Dark One.
Save the Bear from the Watchmen after the fight.
Kill Pavel.
See all Visions in the Dead City.
Disarm 10 Traps.
Find out about the Reds' plans.
Open 10 locked safe boxes.
Kill the Rhino.
Kill 100 Mutants.
Find and return the crying child's Teddy Bear.
Drink at every occasion.
Rescue the Women and Children on the BANDITS level without raising alarm.
Kill 100 Human Enemies.
Spend 30 minutes' worth of Filters.
Kill all armed enemies on the REVOLUTION level, including all reinforcements.
Turn off 40 Lights without breaking them.
Use 10 Lever Switches.
Escape from the Red Line.
Watch the entire Theater Show.
Complete the ECHOES level undetected by the Watchmen.
Make 10 Spiders flip belly-up.
Burn 50 Cobwebs.
Complete the FACILITY level without killing or raising alarm.
Stealthily kill 15 Enemies.
Kill 10 enemies in a row with Throwing Knives.
Escape the chasing Nazis on the REICH level without being caught once.
Free the Prisoners.
Finish the ASHES level without taking a hit.
Complete training sequence.
Choose three primary weapons that use different ammo.