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