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