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