I can tell you what I’ve tried to do to create replay value in my game. But first, as you’ve already said, true “puzzles” don’t really have much replay value. It’s like hearing a joke or a riddle if you already know it. I can go back and relay a puzzle game I played years ago, and still get some enjoyment out of it. But that’s usually because I’ve either A) Forgotten most of the puzzles, so it’s kind of like solving them for the first, or B) It’s nostalgic and fun for other reasons, like mostly enjoying the story.
So, “Replay Value” and “puzzles” really are at odds with each other. I think that pretty much by definition, puzzles don’t/can’t be replayable. At least not in a satisfying way. So, if you want to add “replay” value to your game, I think what you’re looking at is adding alternate content that isn’t necessarily a puzzle. At a high level, think of mini games within a larger game.
As for how I’ve personally approached this, it’s broken into two main topics:
- Optional extra content
- Alternate game modes
In my game, so far, there are about 50 levels. The game is completely linear, but it’s also designed to be (hopefully) approachable to a wide range of player skill. However, hidden within most of the levels are optional extra-hard challenges. Sometimes those are pure puzzles, sometimes they’re more platforming challenges. They’re all optional, and players can choose to engage or not. In practice, most players prefer to come back and do that content later, after playing the “main” game. So, in one sense, you could call that “replay” value, but not really. That content is still the kind of stuff players will probably only do once. They just do it later on. So, it’s probably not fair to call this “replay” value. But it mostly feels like it’s replay value, since it’s optional, more challenging, and you usually come back later after “playing” the normal game. I’m not yet sure what percentage of players are actually interested in coming back and doing the optional content. I’d say it’s probably in the range of 10-20% of players try it out, with a much lower percentage doing all of the optional content.
The other thing I’ve included in my game is an alternate game mode where you try to speedrun individual levels. This was a really easy thing to add into the game, since it’s mostly just a bit of UI to show a timer and a few other things. But this sort of thing tends not to be very popular. Personally, I might enjoy this kind of content for a very short time, mostly to test how good my skills are. But I’m not going to spend hours perfecting speed running techniques in levels. So I think that hardly anyone really wants to do speedrunning, given the option. But again, it was an easy thing to include, and technically it has a lot of replay value, as long as you like that kind of gameplay.