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