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