Here is the full list of all 12 Half-Minute Hero: Super Mega Neo Climax achievements worth 200 gamerscore.
Cleared Hero 3.
Cleared Hero 300 in Hard Mode.
Cleared Hero 300.
Received every title.
Got all available equipment in single player mode.
Cleared "Cursed Hero" without defeating Sasha.
Reached every ending in Hero 30.
Cleared Hero 30.
Allied with all available NPCs.
Offered a total of 3000G to the Goddess in a quest in single player mode.
Became 30 times the True Hero in multiplayer mode.
Prayed to the Goddess for the first time in single player mode.