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