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