"Sequels don’t simply have to be retreads of their predecessors, though – as long as you put some thought into them before you’ve even finished the first game: “The important thing is to try to define some key innovations to sequels in the early stages of pre-production,” Denny states in an article on Eurogamer, “to ensure the experience remains compelling and exciting for the consumers.”"
What about offering compelling new experiences within sequels?