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