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.
Destroy D6.
Complete the SNIPER TEAM level.
Stealthily kill 15 Enemies.
Complete the SPIDER LAIR level.
Complete the KSHATRIYA level.
Disarm 10 Traps.
Complete the ANNA level.
Finish the ASHES level without taking a hit.
Complete the TOWER level.
See all Visions in the Dead City.
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.
Kill 10 enemies in a row with Throwing Knives.
Complete all 43 of Artyom's hidden Diary pages.
Kill Pavel.
Kill the Watchmen attacking the Railcar without taking any damage.
Complete the game in Survival Mode.
Spend 1 hour on the DEVELOPER level.
Complete the KHAN level.
Complete the PAVEL level.
Open 10 locked safe boxes.
Complete the HEAVY SQUAD 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.
Find out about the Reds' plans.
Kill 100 Human Enemies.
Complete the BRIDGE level without a kill.
Remove your mask when Lesnitsky demands it.
Kill the Rhino.
Kill 100 Mutants.
Spend 30 minutes' worth of Filters.
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.
Make 10 Spiders flip belly-up.
Complete the REVOLUTION level without killing and raising an alarm.
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.
Burn 50 Cobwebs.
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.