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