What does backwards compatibility mean?

With respect to Dungeons & Dragons 2024 edition, it is very confused. Honestly, the game is mostly compatible with Dungeons & Dragons 5E (2014), but there are areas where it falters.

Subclasses are an obvious one. The levels of the subclasses change; in 2024, they’re all starting at level 3, which was not the case in 2014.

A more subtle point is that some subclasses build on class abilities – but not all class abilities of 2014 are in 2024 or are gained at different levels. So, a 3^rd party subclass may no longer work with a 2024 class.

I discovered another area where the compatibility falters. When running Kobold Press’s Empire of the Ghouls on Monday, the book called for some poisonous snakes. Well, they no longer exist in 2024, but the conversion guide in the Monster Manual states that you use venomous snakes instead. No problem!

Except, Empire of the Ghouls gave an additional effect for these snakes when you fail your saving throw against their poison.

“If the participant fails the saving throw against the snake’s poison damage, the participant doesn’t take damage, but instead falls unconscious.”

This worked in 2014. Poisonous snakes had this attack:

“Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 1 piercing damage, and the target must make a DC 10 Constitution saving throw, taking 5 (2d4) poison damage on a failed save, or half as much damage on a successful one.”

In 2024, the venomous snake has this attack:

“Bite. Melee Attack Roll: +4, reach 5 ft. Hit: 4 (1d4 + 2) Piercing damage plus 3 (1d6) Poison damage.”

Oh look, no more saving throw! So the modification to the attack given in Empire of the Ghouls no longer works – and the story point that relies on that saving throw falls apart.

Now, I’m an experienced DM who has used both 2014 and 2024 rules now. But for a new player with just the 2024 books and picking up Empire of the Ghouls, this is confusing – and puts the lie to the idea that the rules are backwards compatible.

I’m sure you’ll be able to find other areas where it breaks. The 2014 and 2024 rules are mathematically compatible to a large extent. You can use 2014 monsters and 2024 monsters together in the same game without much problem, likewise have both 2014 and 2024 characters in the same game – I’m doing so at the moment!

There are lots of reasons to enjoy 2024 rules and use them happily with 2014 material as well.

But backwards compatible? Nah.