Converting Adventures from One Game (or Edition) to Another

 

Certain published adventures in certain RPGs are considered classics, and there may be certain adventures that you personally love and it would be a shame to leave them behind if you change games or move to a different edition of a game. This happens to me in particular with D&D but I'm going to talk about other games as well.

First, why use an old adventure in a new game? Well, because I like it a lot mainly. Some adventures, especially with D&D, are touchpoints one can share with many people across multiple editions of the game - Keep on the Borderlands, The Giant series, Isle of Dread, Hommlet and the Temple of Elemental Evil are just a few examples. For Runequest it might be Snake Pipe Hollow or just exploring the city of Prax. For Mutants and Masterminds it's Time of Crisis (probably the only published superhero adventure I actually like). For Gamma World it's Legion of Gold. For Star Wars it might be Tatooine Manhunt. There are many ...

• Though I may have run or played these in the past I might have a group of players that have never been through them but are interested in some classic old-school stuff.
• My players may have started them at some point but never got to finish them. If everyone is interested why not revisit one and give them a chance to close that loop?
• Maybe I ran them some time ago and feel like I could do a better job now or have an idea to change up some elements that would flow really well with this group of players and characters.
• Maybe we want to test out a new set of rules against a known scenario - does it feel similar? Easier? More difficult? It can be an interesting experiment.

Second, what do you have to consider when adapting these things to a new game?

• I'm going to lead off with "setting" - as it's not just the mechanics we need to check. Does it make sense as far as time and place and NPCs and organizations or power groups within the baseline of your new game or are you going to need to adjust some expectations. Many games mix the setting and the rules into one mish-mash and a new edition means setting changes as well as rules. You need to find a place to work it in. Old D&D adventures tend to be pretty generic as far as location other than some geographic features so they are pretty easy to drop in but some editions also update their settings and kill off gods - you might need to re-work a few things if Bane is no longer the big evil power in the Realms.
• Characters - Are characters built and presented differently in the new game compared to the old game? Is there a level range involved? How different are the mechanics for the PCs in the new vs. the old? Imagine trying to run Keep on the Borderlands for a Rifts campaign ... yeah that's just not a great fit for a typical Rifts party unless you make a -lot- of adjustments - likely to the point of unrecognizability. Expedition to the Barrier peaks? Now that might work.
• Encounter Structure - D&D 3E & Pathfinder started and then 4E perfected the concept of X number of encounters per level of various challenge ratings all calculated up to provide a certain level of XP to allow the PCs to progress through the adventure at the appropriate pace and the appropriate level. That's not going to be relevant to your new game. If your new game has something similar you are going to need to re-work it using those rules if it matters to you.
  In contrast a game like Savage Worlds does not care about that at all. If it does not have that kind of structure then I typically look to the flavor of the adventure - it's not the exact number of stormtroopers are guarding the docking bay - it's that there are some stormtroopers guarding the docking bay and you need to sneak/persuade/bribe/shoot your way past them to get to the ship and if a fight breaks out you only have a limited time before reinforcements start showing up.
• Monsters can also vary dramatically from game to game and edition to edition - don't get caught up in exact monster levels or stats, try to keep the flavor of the thing. If there's a Behir in a cave and your game doesn't have a Behir or they are too powerful or too weak for where your PC's will be then maybe it's a dragon of some type. If another cave has a singular minotaur but in the new game that's not much of a challenge to the party then maybe it's a minotaur chieftain and some followers. If your players are talking afterwards about "those minotaurs" rather than "that minotaur" then you're still doing it right.
• Pacing - D&D has XP for monsters defeated and a milestone system where PC's level up at certain points in the story. Old school Runequest grants a chance to improve skills just for using them. The current edition of Savage Worlds uses per-session XP with advances granted after a certain number of sessions. An adventure may make certain assumptions about party advancement during the course of the adventure - it's usually worth taking a look at that and seeing how it will work with your system of choice. 
• General Mechanics - Old D&D had no skill system. Many newer versions of it and many other games do. That means there are no target numbers for things in those old adventures like finding secret doors or avoiding traps or leaping over pits or climbing walls. Your new system should have some baseline guidance on what easy/average/difficult tasks should be and in my experience that should be enough but if you want to assign some specifics you're going to have to come up with those yourself. That's just one example.
  

Having done this a few times over the years I can say after thinking through the things above there are some other points to consider:

• It's not really all that difficult to adapt a D&D adventure to some other edition or version of D&D. Pick the setting, make some notes on DC's if you need them and then start adjusting the monsters. Since D&D tends to have the same monsters and races and settings across the editions all you need to do is ensure you have the statblocks you need for your chosen edition. Goblins, bugbears, ogres, trolls, dragons - they all tend to stay around the same level range across editions though I would advise against pulling these on the fly - there are occasional outliers that can be much tougher or much easier than you - or your players - probably want. AD&D 2E's update to dragons compared to what they were in 1E is a good example.
• Adapting an adventure to a very different set of mechanics within the same genre is more complicated but still doable. I ran a short RQ2 campaign using Caverns of Thracia as the adventure so a lot of my GM processing power was used in on-the-fly rulings on when a skill check was needed and whether any modifiers applied. I had monster stats picked out ahead of time so that wasn't a drain. That said moving an old Judges' Guild adventure into the framework for an old percentile-based system was an adjustment but one I could manage mostly live. 
• Adapting completely different systems and genres - this is a little trickier and probably rare but sometimes inspiration strike and your knights and wizards or cowboys and mad scientists need to go up against the Legion of Gold or Cylons or the 21st Panzer Division. In this case you need to look at what you do have:
• You have an overall situation that you presumably want to keep
• You have maps!
• You have NPC descriptions and motivations
• You have a list of the opposition
• You have some idea of what the prospective group of PC's can do

    That's plenty! Again we are mostly working out numbers for the new game - target numbers, statblocks for monsters and vehicles, and equipment/loot if that's a thing. For Star Wars & Superheroes it doesn't usually matter but for D&D and Gamma World it will.

Some of these conversions are pretty easy. Updating Time of Crisis for M&M was really just a matter of new stats for the characters encountered. It's a 1E adventure and Green Ronin did publish a conversion in the 2E GM screen which made it even easier and then somewhere along the way the stats one would need for a 3E conversion came out as well. 

Examples I have done:

• I ran Red Hand of Doom (a large 3.5 adventure/campaign) in 4th edition - recap here - and it was fairly easy because it is still a recent (at the time) D&D adventure with all of the D&D assumptions. I ran it in Impiltur in the Forgotten Realms which involved a bit of customization beyond systemic stuff but a lot of my effort was spent working out how it should work within 4E's level and encounter framework - basically getting the math right, at least according to the designers. The thing is I really enjoyed that part! The challenge of keeping the original flow and monsters and situations while making it work within a new framework ... yes that was a lot of fun and then seeing it play out with a really nice level of challenging but not deadly was pretty gratifying. Most of the effort was going through each part and saying "alright we have an ambush by a bunch of bugbears here - how many and what types make sense here for level X?", adding in skill challenges where appropriate, and then typing up my notes. It worked really well and it helped that I was coming out of doing it for two prior campaigns. 
• Of those two prior campaigns one was a 4E version of Temple of Elemental Evil and one was a conversion of Pool of Radiance, er, "Ruins of Adventure". 
• ToEE was again pretty straightforward as I was trying to run it largely as-written so it was mainly a matter of determining what level each part of the wilderness or moathouse or dungeon was and then dropping in the new statblocks for those creatures on a cheatsheet to use while running. It might have been the easiest of all of these because it's so easily divided up - breakdown here.
• Return to the Ruins of Adventure was my first 4E campaign and it was not a strict conversion - more of a loose interpretation of the gold box computer game and the paper module associated with it. Like ToEE it was pretty easy to structure it for 4E with each area being a certain level and having a certain number of encounters but I had a blast deciding what to put where and linking the encounters in narrative ways where it felt right and figuring out how skill challenges could fit in for the first time. This was also mainly a structure and statblocks conversion as the scenario was already solid and it was still a D&D adventure. 
  
  
  
  
  
• I am running the Temple again ten years later using Tales of the Valiant but this time I have a 5e conversion from Goodman Games that handles a lot of the details and all I have to do is sub out the boring 5E monster stats for the more interesting ToV Monster Vault (and other books) versions which is ridiculously easy to do. This is a truly easy mode conversion
• As far as 5E D&D conversions most of the ones that have been published have been solid to excellent. WOTC published some in Tales from the Yawning Portal, staying very faithful to the originals. The Goodman Games conversions are just excellent, putting a copy of the original and then a 5E update in the same book in most cases and adding in some optional extra material where the original is a little thin. I've run both the B1/B2 combo package and Isle of Dread in 5E and I am very happen with them.
• Old Traveller adventures are handy drop-ins for some Star Wars campaigns and I've run the 3-part starter campaign for Star Frontiers in both d20 Star Wars and d6 Star Wars as I think it's a really good fit and it's mostly a statblock-swapping exercise: Space pirates attack a ship? I just pick out Star Wars space pirate stats. The characters travel in an air raft or are attacked by a jetcopter? I pick out an airspeeder. Traveller free trader/far trader = YT1300 - it's not hard, you just have to work through it to prep.

That's probably enough rambling on this topic but I wanted to get it out there -  just because the rules change doesn't mean you can't use an old favorite again - or for the first time!