Escape from the Sector 1 Reactor with 7:45 or more remaining.
Steal a kid's life-savings.
Don’t let Aerith fight at Sector 5 Church
Do at least 20 squats at the gym.
Get Don Corneo to choose Cloud over the two females.
Use a grenade on Rufus.
Escape from Midgar.
Get through Cloud's flashback with Sephiroth.
Get the fat chocobo instead of the normal chocobo when using the Choco_Mog summon.
Beat the Midgar Zolom before viewing the scene with the dead Zolom.
Have Yuffie join your party.
Beat Bottomswell using nothing but limit breaks.
Get more than 50% ratings in the Shinra march.
Get Rufus' mood above 100 in the Junon sendoff.
Loot the Cokatolis nest on Mt. Corel.
Win the Chocobo Racing mini-game.
Have Vincent join your party.
Obtain every Turtle's Paradise poster and obtain your reward.
Complete the Stolen Materia sidequest.
Go on a date with Barret in the Gold Saucer.
Complete Battle Square with Aerith.
Obtain the Bahamut Materia.
Complete the Temple of the Ancients using magic only, initial equipment, without healing at an inn (full rules in comments).
Defeat Jenova LIFE.
View a hidden scene with Ilfana and Professor Gast.
Obtain everything in the Great Glacier.
Kill a Marlboro without any status resistances after it's used Bad Breath on you.
Defeat Jenova DEATH before her 4th turn.
Get through the events on the Northern Crater
Win the slap fight against Scarlet
View the Xenogears reference.
Complete every optional Fort Condor mission.
Steal a Cursed Ring from Ultimate Weapon
Find out what really happened in Nibelheim.
Defeat both Turks in Gongaga.
Learn Cosmo Memory.
Learn All Creation.
Learn Great Gospel.
Learn Catastrophe.
Visit the church on disc 2 to see a special someone.
Obtain Tifa's ultimate weapon.
Learn Final Heaven.
Get 7 "Yeah!"s on Tifa's limit break.
Solo Carry Armor with any character (other chars must be dead for the whole battle).
Obtain Cid's ultimate weapon.
Learn Highwind.
Obtain Yuffie's ultimate weapon.
Obtain Vincent's ultimate weapon.
Learn Chaos.
Obtain all 4 Huge Materias.(Must have them all in inventory before dropping off at Cosmo Canyon)
Master your first materia.
Defeat the Diamond Weapon.
Defeat Diamond Weapon using nothing but limits.
Learn Slots.
Learn what happened to Don Corneo.
Defeat all 3 Turks at Midgar
Obtain Cait Sith's ultimate weapon.
Obtain Barret's ultimate weapon
Defeat Hojo.
Solo Hojo while only using Vincent's Chaos limit break.
View a hidden scene with Tifa at the end of disc 2.
Finish a battle with Cait Sith's Game Over technique.
Obtain Red XIII's ultimate weapon.
View the flashback that shows Cloud escaping Nibelheim.
Complete the first phase of the Ultimate Weapon fight in one battle.
Obtain Cloud's ultimate weapon.
Complete the Ancient Forest.
Complete the Mog's House minigame.
Win against The Wrestler in the Arm Wrestling minigame.
Score 10,050 points or more in G-Bike at the Gold Saucer.
Double your GP prize in the Super Dunk minigame.
Complete the Crazy Course in the Snowboarding minigame with 70 or more points.
Complete the Beginner Course in the Snowboarding minigame with 90 or more points.
Complete the Expert Course in the Snowboarding minigame with 90 or more points.
Complete the Crazy Course in the Snowboarding minigame with 90 or more points.
Complete the Undersea Mako Reactor Battle in Torpedo Attack.
Complete Level 1 of Torpedo Attack.
Complete Level 2 of Torpedo Attack.
Complete Level 3 of Torpedo Attack.
Complete Level 4 of Torpedo Attack.
Obtain 5000 or more points in the Speed Square.
Learn Omnislash.
Complete the special battle at Battle Square.
Buy the house at Costa del Sol.
Beat Joe's chocobo, Teioh in a race.
Complete the Materia Caves quest.
Obtain a Master Materia through materia fusion.
Get any character to 7777 HP in battle.
Do 9999 points of damage to an enemy.
Obtain every enemy skill on one materia.
Defeat the Ruby Weapon.
Defeat the Emerald Weapon.
Complete the Kalm Traveler quest.
Defeat both forms of Sephiroth at full power without using Knights of the Round or Game Over.
Complete the game.
Complete the game without anyone surpassing level 28.
Beat Palmer using nothing but limit breaks (Game Over banned).
Defeat the Materia Keeper without him healing himself using nothing but items.