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.
Complete the SNIPER TEAM level.
Complete the TOWER level.
Complete the SPIDER LAIR level.
Spend 1 hour on the DEVELOPER level.
Complete the PAVEL level.
Complete the KHAN level.
Complete the ANNA level.
Finish the ASHES level without taking a hit.
Kill all armed enemies on the REVOLUTION level, including all reinforcements.
Complete all 43 of Artyom's hidden Diary pages.
Save D6.
Complete the game in Spartan Mode.
Kill Pavel.
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.
Complete the FACILITY level without killing or raising alarm.
Complete the SEPARATION level without killing or raising alarm.
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.
Open 10 locked safe boxes.
Find out about the Reds' plans.
Kill the Rhino.
Disarm 10 Traps.
Spend 30 minutes' worth of Filters.
Find and return the crying child's Teddy Bear.
Kill 100 Mutants.
Kill 10 enemies in a row with Throwing Knives.
Stealthily kill 15 Enemies.
Make 10 Spiders flip belly-up.
Escape from the Red Line.
Watch the entire Theater Show.
Complete the ECHOES level undetected by the Watchmen.
Burn 50 Cobwebs.
Kill 100 Human Enemies.
Use 10 Lever Switches.
Turn off 40 Lights without breaking them.
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.