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