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