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