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.
Complete the ANNA level.
Complete the KHAN level.
Complete the PAVEL level.
Spend 1 hour on the DEVELOPER level.
Complete the SPIDER LAIR level.
Complete the TOWER level.
Complete the SNIPER TEAM level.
Complete the KSHATRIYA level.
Complete the HEAVY SQUAD level.
Remove your mask when Lesnitsky demands it.
Kill Pavel.
Open 10 locked safe boxes.
Make 10 Spiders flip belly-up.
Find and return the crying child's Teddy Bear.
Kill 10 enemies in a row with Throwing Knives.
Drink at every occasion.
Disarm 10 Traps.
See all Visions in the Dead City.
Complete the REVOLUTION level without killing and raising an alarm.
Kill all armed enemies on the REVOLUTION level, including all reinforcements.
Complete all 43 of Artyom's hidden Diary pages.
Destroy D6.
Complete the game in Spartan Mode.
Make Moskvin tell the truth with help from the Dark One.
Save the Bear from the Watchmen after the fight.
Find out about the Reds' plans.
Complete the BRIDGE level without a kill.
Burn 50 Cobwebs.
Kill the Rhino.
Spend 30 minutes' worth of Filters.
Kill 100 Mutants.
Rescue the Women and Children on the BANDITS level without raising alarm.
Kill the Watchmen attacking the Railcar without taking any damage.
Kill 100 Human Enemies.
Use 10 Lever Switches.
Turn off 40 Lights without breaking them.
Escape from the Red Line.
Watch the entire Theater Show.
Complete the ECHOES level undetected by the Watchmen.
Complete the FACILITY level without killing or raising alarm.
Complete the SEPARATION level without killing or raising alarm.
Stealthily kill 15 Enemies.
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.