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