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