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