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