While God of War has become synonymous with big, hack 'n' slash action, it was Devil May Cry that first brought it to the PS2 and made it a very popular genre in the west. Capcom had been making sequel after sequel when Devil May Cry appeared out of nowhere and took everyone by surprise. A much appreciated surprise.
Playing as private investigator Dante, you enter the Demon world to avenge the death of his mother and brother. Funnily enough, Devil May Cry started out as another sequel - a Resident Evil game to be exact. This, amazingly, was the embryonic version of Resident Evil 4, a game that may show up later in this list.
Devil May Cry was a very stylish Gothic horror game that infused hack 'n' slash sword-fighting with dual gun-wielding. A great game that spawned several sequels and a reboot.