Cross-system Modules

[Nibellius]

I'm starting a new campaign and I have very little experience with GMing. I've noticed that 5e has a lot of really nice, interesting and free modules but our group really wants to play 3.5e. I read through some of the modules and wondered if there are any hidden problems with running them in an older system, appart from changing the monsters a bit and perhaps tweaking the treasure. I was thinking about Out of the Abyss (Starter), Death House, Princes of the Apocalypse, etc.

[Grod_The_Giant]

Off the top of my head...

• You'll need to rewrite every encounter, particularly since 5e monsters stay relevant threats much longer than their 3.5 equivalents.
• You'll need to rewrite treasure significantly, since 3.5 requires a certain (high) number of magic items just to keep your basic attacks/saves/AC relevant.
• You'll need to check plots carefully to make sure there aren't obvious spells that'll circumvent them. It's 3.5, so there will always be some spells that'll circumvent everything, but you'll want to be careful-- ie, Out of the Abyss would be a lot less scary with 3.5's "hide all night in perfect safety" version of Rope Trick.

Not to mention that they're not free, apart from a handful of starter adventures like the Death House. You'd probably be better off looking at 3.5 or Pathfinder modules-- stuff like Red Hand of Doom, Sunless Citadel, Skull and Shackles, and the like.

[Nibellius]

Thanks for the quick reply. Usually the monsters are in both editions so for example if it says that a grey ooze drops in I could just use the ooze from 3.5e or are they too unbalanced? Can't all plots be destroyed with 3.5e spells?

[Anonymouswizard]

I'm starting a new campaign and I have very little experience with GMing. I've noticed that 5e has a lot of really nice, interesting and free modules but our group really wants to play 3.5e. I read through some of the modules and wondered if there are any hidden problems with running them in an older system, appart from changing the monsters a bit and perhaps tweaking the treasure. I was thinking about Out of the Abyss (Starter), Death House, Princes of the Apocalypse, etc.

D&D 3.5 scales faster in terms of numbers, required magic items (in 5e it's slow enough that you can still beat end game enemies without them, in 3.5 you can't [unless you're a full caster]), and ability for magic to solve problems.

Bare in mind that 5e is already in the high leagues of PC power growth, so using 5e instead of GURPS, DSA, or Savage Worlds means you have less work to do.

Now I can't remember the required pluses treadmill for 3.X, because it wasn't as obvious as 5e, but +1 weapons should be appearing while the PCs are still 1st-3rd level and +5 [words] weapons available by level 20. Monsters also scale faster in 3.X, while the CR system is broken as a very rough rule fights should have a final CR of the party's mean Effective Character Level if they're to be 'fair', and within 4 CR unless they're supposed to be particularly easy/hard.

[Grod_The_Giant]

Thanks for the quick reply. Usually the monsters are in both editions so for example if it says that a grey ooze drops in I could just use the ooze from 3.5e or are they too unbalanced?

Definitely not-- to take just your example, a grey ooze is a CR 1/2 monster in 5e that slowly weakens mundane weapons; in 3.5 it's a CR 4 enemy capable of instantly destroying your most valuable enchanted weapons and armor with a single failed save. You'll have to look at each encounter holistically, and say "okay, I need a dangerous ooze-y encounter for a level 1 party, what can I find in 3.5 that fits the bill?"

Can't all plots be destroyed with 3.5e spells?

Yes. But sometimes it takes an active effort, and sometimes it takes "whoops, I forgot Teleport used to be a 5th level spell."

Oh! You'll also need to totally rewrite all DCs.

[Nibellius]

OK, thanks to both of you I now know that it's a bad idea although it didn't seem that bad at first.

[Knaight]

Thanks for the quick reply. Usually the monsters are in both editions so for example if it says that a grey ooze drops in I could just use the ooze from 3.5e or are they too unbalanced? Can't all plots be destroyed with 3.5e spells?

Th monsters are generally kept conceptually, but implementations can differ hugely. Even beyond that there are fundamental differences in scaling - each level in 5e accumulates less power than a level in 3.5, which makes any fight against creatures at a significantly different level than the PCs sketchy even if they're the same CR in each edition. Similarly the default assumption of how many creatures there are per fight is different in each edition, which also throws everything off.

If you want to run modules, find 3.5 modules. Fortunately for you it's a game with a huge module collection (that's one of the big advantages of D&D in general, compared to literally everything else).

[redwizard007]

Thanks for the quick reply. Usually the monsters are in both editions so for example if it says that a grey ooze drops in I could just use the ooze from 3.5e or are they too unbalanced? Can't all plots be destroyed with 3.5e spells?

Take a look at the specific monsters in each edition and adjust as necessary. They will usually look fairly close, but there will be instances where adjustment is needed. My best advice is to completely convert a few encounters and run a simulated group through them (probably run by a single friend.) That should give you a baseline from which you can determine what changes to make.