Maybe it wasnt really the hardest game that i have played, but FF X was the most punishing game for me.I had to create strategies for a lot of bosses because they would simply pwn me otherwise.I still have nightmares with the final boss.
My (locked) thread about how difficulty should be a decision for the developers, not the gamers.
https://gamrconnect.vgchartz.com/thread.php?id=241866&page=1