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