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