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