Make a game with spells, or interesting status effects that can be inflicted upon characters. These could be "area of effect" spells, arcane spells, dark souls spells, buffs/debuffs, you name it. I include buffs and debuffs because they're just as interesting as spells in my opinion. For ideas, think of Fromsoft, Blizzard Entertainment, JRPGs, MMORPGSs, etc.