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