You have to see games differently from other software. Treat games as consumables, that are meant to be finished. Once a player finishes a game, the desire to replay it soon after is going to be pretty low, no matter how good the experience was.

However, players will desire more of that similar experience. Ask anybody who just finished a good game and they'll tell you how finishing it left a void, and that they're looking for a similar game to fill that void again. Once you see this, it's easy to understand why there is an ocean of very similar games out there that still manage to sell in good numbers.