Isaac appears as one of Dracula's allies in the first Pachislot Akumajō Dracula game. As it is not clear if the events of Castlevania: Curse of Darkness are relevant to this game or not, it is not clear if this is implying that Isaac survived the events of Castlevania: Curse of Darkness. Isaac's Chauve-souris has been replaced with a giant spiked iron ball and chain in this game. He and Trevor essentially lock chains over a chasm between towers and attempt to pull each other into the abyss below.
Pachislot Akumajō Dracula
KPE Dream Master