I've written about the RPG metagame debate before, and one contributing factor to what I'll call "metagame anxiety" is familiarity with an adventure. For the record, I don't usually mind the metagame. I believe it can be a fun and valuable part of the game. But some people get concerned that a player might be familiar with an RPG module, and they believe that any level of familiarity renders that module useless. After all, how can a game be fun when the player already knows the plot of the adventure? How can it be a challenge when a player already knows the key plot points? But I find replaying RPG adventures to be a lot of fun, and I think we don't generally do it often enough.
The fear that adventures are single-use is entirely illusory. But people fall for it, even though they themselves may have played through their favourite video game more than once, or watched their favourite movie or read their favourite book more than once. I don't know why we do it, but we do seem to make an exception for RPG adventures. We tell ourselves that, for whatever reason, an RPG adventure just can't work more than once.
I believe there are two reasons we think an adventure is only good for one play-through.
As the DM, do I have to pretend like my players have never heard the description of Alleyway #3? What if I forget to mention the barrel in the corner? Without it, they'll be unable to step up on it to find the key on the ledge. And if they don't find the key, then how will they get into the room?
It can be equally as confusing for a player. Last time there was a barrel in the corner, and I climbed up onto it to search the ledge, where I found a key. Did the DM forget to mention it, or is this a plot twist to make the game feel different than last time? Was the barrel randomly generated?
Can I ask whether there's a barrel in the corner? Why would I? It would be metagaming to ask about a specific object that the DM didn't mention.
Well, that's not fun for anyone.
The fact is, there are lots of adventures out there. RPG companies publish lots of adventures for their games, and there are usually third-party adventures available on DriveThru. You may as well treat adventures as ephemera, because the more you linger on one, the fewer you'll get to play before your CON score is reduced to 0 by old age.
Those are both valid points, and combined they're really good arguments for not playing the same adventure twice. But I've played adventures more than once, and I find that the bond I form with a module I play more than once is a lot stronger than an adventure I get through and then summarily forget.
Exploration is one of the best parts of an RPG. There's nothing quite like stepping into an imaginary space, lighting an imaginary torch, and then hearing from the Dungeon Master what mysterious room your character has discovered.
When you play a module you know nothing about for the very first time, that sense of discovery can be mind-alteringly intense. The second time around, presumably, is less exciting. Instead of the DM telling you what your character sees, you can probably tell the DM what your character sees, because you (the player) have already been there on your last play-through. At least, that's what you might think if you've never replayed a module before.
What actually happens is that you get to experience your character's discovery all over again, because while you (the player) have been to Alleyway #3 before, your character has not. This character isn't the same as your previous character. You're likely playing a different class, or at the very least you have different stats. And anyway, it's a roleplaying game, so even in the improbable case you're playing the same class and have the exact same stats, the character is still unique. Your new character is looking for different things in Alleyway #3, their approach to that space, however familiar it may be to you as the player, is different.
Your no-nonsense fighter or your pragmatic monk noticed the barrel leading to the key leading to the door, but your sneaky rogue doesn't need a key, and your bard isn't too proud to crawl through that storm gutter leading up into the building's basement, and your wizard's just going to Dimension Door anyway, and so on.
That's the discovery that you (the player) get to experience, equally as powerfully, each and every time you replay a module. You get to experience the same space from a completely different viewpoint.
Discovery isn't always mechanical. It doesn't always involve finding a clue to the next plot point. Sometimes, exploration is really just about exploration.
When you're confronted with objects and places you've already experienced, then take a moment to look at the details. Ask about aspects of objects that you might not have thought to ask about during the first play-through. Your new character has unique skills and a background, so put them to use. One person's trash is another's treasure, so a character with the street urchin background is going to fawn over a bauble that the noble character sees as literal trash. A magic user sees things differently than a mundane character does, and interacts with objects with different goals in mind.
Find the differences in how your previous character and your current character perceive the same space and the same objects. Compare that difference, consider how they influence your actions, and take pride in your own ability to walk into a familiar space and yet to "see" it through an entirely new lens.
And most importantly, let that difference in perception change the way you play your character's response and interaction with the environment.
The great thing about most RPGs is that they empower players to find their own fun. If you're a player who enjoys crafting wacky inventions from everyday objects, you can make that your character's primary goal. If you enjoy combat, you can ensure your character gets into lots of fights. If you enjoy social intrigue, you can snoop around and listen through doors all day long. You name it, your RPG can probably provide, and if it can't then some other RPG system can.
When you play through an adventure the second time around, it may be that the plot necessarily becomes a secondary concern. Admittedly, it depends on how thorough you were in your first play-through, and how much material the adventure provides (or how much the DM is willing to add to it), so it may be that an adventure can take you in a completely different direction the second time around. But assuming the "worst" case scenario of a simple linear dungeon crawl, then the plot probably won't be the thing that captivates you on your second play-through. And for being the worst case, that's not bad, because it's exactly the same as a video game.
There's more to an RPG than plot. Pick a win condition and play the adventure for that. Or pick an arbitrary restriction and play the adventure accordingly. Nobody's keeping score but yourself. Sure you died a horrible death during the final boss fight, but darn it, you vowed to use nothing but Illusion spells during this adventure, and that's what you did, so you win.
One of the most memorably boring fights I've ever been involved with was when a party was attacked by a gang of oozes. The oozes could only move 10 and 20 feet, so the players just kept backing up each round, the oozes kept splitting (creating more oozes), and the battle went on and on. But you know what? We learned so much about our characters during that fight. Little mechanics about how our characters functioned came to light as we explored every nuanced way we could kill the oozes slithering slowly toward us each round.
Replaying an adventure is a great way to try and learn a new character build. In a brand new adventure, everything's a threat. You have no idea what's a devious trap, what's a random encounter, or whow long your character has to live. You don't experiment with your character's life in a new module, you use what you know. And if that thing is the same thing from level 2 to 20, then you're going to use it for as long as it's working.
In an adventure you already know, however, you're likely to be a little more adventurous with your character. There are certain threats you can anticipate, safeguards you can rely upon, and you can take the time to experience a new class, or a new sub-class, or a collection of new feat combos. You can afford to try out different spells than the ones you normally rely on. You can finally try a build you'd never have tried under pressure.
My assumption in this article is that the DM changes nothing from the original text, but of course most Dungeon Masters wouldn't do that. Most Dungeon Masters won't be able to resist adding in some variation, which can make a second play-through a lot different than what you might expect.
Either way, adventures are fun when re-played. If you've never tried it, I recommend at least giving it a chance. Play a short adventure through, and then flip right back to the beginning of the book and play it again with a new character.