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 Pavel.
Spend 1 hour on the DEVELOPER level.
Complete the TOWER level.
Complete the KSHATRIYA level.
Kill 10 enemies in a row with Throwing Knives.
Complete all 43 of Artyom's hidden Diary pages.
Kill all armed enemies on the REVOLUTION level, including all reinforcements.
Complete the game in Spartan Mode.
Drink at every occasion.
Watch the entire Theater Show.
Complete the SEPARATION level without killing or raising alarm.
Complete the ANNA level.
Complete the KHAN level.
Complete the PAVEL level.
Complete the SPIDER LAIR level.
Complete the SNIPER TEAM level.
Complete the HEAVY SQUAD level.
Open 10 locked safe boxes.
Disarm 10 Traps.
Complete the BRIDGE level without a kill.
Rescue the Women and Children on the BANDITS level without raising alarm.
Complete the REVOLUTION level without killing and raising an alarm.
Finish the ASHES level without taking a hit.
Save D6.
See all Visions in the Dead City.
Burn 50 Cobwebs.
Remove your mask when Lesnitsky demands it.
Make 10 Spiders flip belly-up.
Complete the FACILITY level without killing or raising alarm.
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 the Rhino.
Kill 100 Mutants.
Turn off 40 Lights without breaking them.
Spend 30 minutes' worth of Filters.
Find and return the crying child's Teddy Bear.
Stealthily kill 15 Enemies.
Kill the Watchmen attacking the Railcar without taking any damage.
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.
Free the Prisoners.
Complete training sequence.
Choose three primary weapons that use different ammo.