Here is the full list of all 20 Shadow Warrior Classic Redux achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Find 70 secret areas
Collect 50 fortune cookies
Kill 500 enemies
Finish any level faster than 3D Realms time
Slice 100 evil ninjas with Katana
Win 10 Pachinko games
Use the Speed Racer RC car
Kill 50 enemies
Watch TV in Seppuku Station
Fire Nuclear Missile
Meet Sailor Moon
Defeat Serpent God boss
Defeat Sumo Demon boss
Find Monty Python and The Holy Grail reference
Breed the rabbits to exhaustion
Finish "Enter The Wang" episode
Finish "Code Of Honor" episode
Finish "Wanton Destruction" expansion
Finish "Twin Dragon" expansion
Hit 20 enemies with a vehicle