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