Heres a guide on how to get all the Achievements in Achievement Unlocked:

#0: Don't Move a Muscle = Keep the elephant from moving
#1: It's a Jump to the Left = Find a way to move westward
#2: And it's a step to the Ri-i-ight! = Strain yourself to move right
#3: Fight Gravity = Figure out how to jump upwards
#4: Elephant Skewers = Hit a spike strip
#5: Ascension = Be lifted into the sky
#6: Lefty = Show love to the left wall.
#7: Righty = Show love to the right wall.
#8: Purple Ceiling = Hit the top of the hardest level
#9: Rock Bottom = Find the bottom of the easiest level
#10: Speedy Downfall = Fall from the top to bottom without stopping
#11: Escape Velocity = Go from bottom to top without stopping
#12: Stalactite = Skewer yourself at high speed on downward facing spikes
#13: Stalagmite = Skewer yourself at high speed on upward facing spikes
#14: Found Point 0 = Uncovered secret point 0
#15: Found Point 1 = Claimed secret point 1
#16: Found Point 2 = Excavated secret point 2
#17: Found Point 3 = Popped open secret point 3
#18: Found Point 4 = Tripped over secret point 4
#19: Found Point 5 = Visited secret point 5
#20: Bloodhound = Uncovered all points on level
#21: Floating Corpse = Get a skeleton stuck in a launcher
#22: I Can Count to 5! = Visit each point in order
#23: We Have Liftoff = Visit each point in reverse order
#24: Airwalking = Stay off the ground for 10 seconds
#25: Hellbound = Launch corpse to bottom
#26: Heavenbound = Launch corpse to ceiling
#27: Secret Alcove = Get surrounded by three sides (1)
#28: Secret Cave = Get surrounded by three sides (2)
#29: Secret Hideout = Get surrounded by three sides (3)
#30: Death at 0 = Fire a corpse at Point 0
#31: 1 o'clock murder = Fire a corpse at Point 1
#32: Get Off Your Seats = Jump for 10 seconds nonstop
#33: Cemetary = Have 5 live corpses on the screen
#34: Graveyard = Have 7 live corpses on the screen
#35: Half-Century = Reach 50 elephant deaths
#36: Century = Reach 100 elephant deaths
#37: And One More... = Hit 101 elephant deaths
#38: Stayin' Alive = Stay alive for 15 seconds
#39: Longevity = Stay alive for 30 seconds
#40: Gone in a Flash = Die in less 0.23 seconds
#41: Wrecking Ball = Hit the center spiked platform
#42: In the Pit = Land a corpse in the pit
#43: Pit Hat Trick = Land 3 corpses in the pit
#44: 10 Pin Pit = Land 10 corpses in the pit
#45: Double Play Pit = Have two corpses in the pit at once
#46: Triple Play Pit = Have three corpses in the pit at once
#47: Horizontal Confusion = Hold both the left and right keys
#48: Vertical Confusion = Hold both the up and down keys
#49: Total Confusion = Space bar has no purpose, dummy
#50: My Favourite Spot = Find the developer's favourite spot
#51: 60 Seconds = Play for one minute
#52: 180 Seconds = Play for three minutes
#53: 300 Seconds = Play for five minutes
#54: Pi = Hit points 3-1-4 in that order
#55: THIS IS SPARTA = Hit 3-0-0 in that order
#56: Meaning of Life = Hit 4-2 in that order
#57: (2*125)+3 = Hit 2-5-3 in that order
#58: 3*(30/(15-13)) = Hit 4-5 in that order
#59: Paint 10 = Touch 10 blocks
#60: Paint 25 = Touch 25 blocks
#61: Paint 50 = Touch 50 blocks
#62: Paint 75 = Touch 75 blocks
#63: Paint 100 = Touch 100 blocks
#64: Masterpiece = Touch every touchable block
#65: Jet 5 = Hit 5 launchers
#66: Jet 10 = Hit 10 launchers
#67: Master Jetter = Hit every launcher
#68: 3 Spikes = Hit 3 stationary spikes
#69: 7 Spikes = Hit 7 stationary spikes
#70: Spikeful = Hit all stationary spikes
#71: Extreme Makeover = Recolour all areas
#72: True Blue = Turn your elephant blue
#73: Shocking Pink = Turn your elephant Pink
#74: Sweet Orange = Turn your elephant orange
#75: Stealth Black = Turn your elephant black
#76: Cheater = Ask for a Hint
#77: Programmers Credit = Enter jmtb02 into level
#78: Too Much Contra = Enter Contra level select code
#79: No Cheese for You = Click the level area
#80: Bandwidth Exploiter = Preload the game
#81: You Are El = Click the Armor Games link
#82: Menu Explorer = Find the main menu
#83: Quality Snob = Adjust the quality
#84: Scrolliastic = Scroll the achievements section
#85: Play the Game = Start the game
#86: Get to Level 1 = Play Level 1
#87: Not Listening = Mute the sound
#88: Clink Clash Clink = Found the sponsor screen
#89: Best Player Ever = Earned an achievement
#90: 10 Percent Done = Earn 10 achievements
#91: 20 Percent Done = Earn 20 achievements
#92: 30 Percent Done = Earn 30 achievements
#93: 40 Percent Done = Earn 40 achievements
#94: 50 Percent Done = Earn 50 achievements
#95: 60 Percent Done = Earn 60 achievements
#96: 70 Percent Done = Earn 70 achievements
#97: 80 Percent Done = Earn 80 achievements
#98: 90 Percent Done = Earn 90 achievements
#99: Too Much Free Time = Earn 99 achievements