Here is the full list of all 45 Final Fantasy VIII achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Reach level 100 with Boko
Reach level 100
Finish the game with Squall's initial level
Kill 10000 enemies
Beat the Omega weapon
Learn all of Rinoa's limit breaks
Reach maximum Gil
Kill 1000 enemies
Learn all of Quistis' limit breaks
Reach maximum HP
Unlock Guardian Force Doomtrain
Finish the game
Collect all cards
Win 100 games of Triple Triad
Unlock Guardian Force Eden
Unlock Guardian Force Bahamut
Complete the PuPu side quest
Draw magic 100 times from draw points
Collect all Weapons Monthly/Combat King/Pet Pals/Occult Fan magazines
Unlock Guardian Force Tonberry
Unlock Guardian Force Cactuar
Complete the Obel Lake side quest
Defeat every member of the CC Group
Acquired an item from Chocobo World
Collect all Timber Maniacs magazines
Find Ragnarok
Reach SeeD rank A
Unlock Guardian Force Alexander
Unlock Guardian Force Cerberus
Capture a Chocobo
Unlock Guardian Force Diablos
Unlock Guardian Force Pandemona
Unlock Guardian Force Leviathan
Unlock Guardian Force Carbuncle
Unlock Guardian Force Brothers
Upgrade your weapon
Kill 100 enemies
Get your first salary from SeeD
Lose a rare card in a Triple Triad game
Draw (Stock) magic from enemies 100 times
Unlock Guardian Force Siren
Unlock Guardian Force Ifrit
Unlock Guardian Force Shiva
Unlock Guardian Force Quezacotl
Play Triple Triad