Advice or guides for helping teach someone 3.5e when they started out with D&D 5e?

[Coidzor]

We're planning a "historical" game in the history of one of our DM's settings to basically play out the events of Red Hand of Doom's Battle of Brindol, and one of the conceits of that setting is that there was an event that happened demarcating the end of 3.5e and the beginning of 5e.

About half of the current group have never played 3rd Edition, though, or even PF1E, so this is about as much about that whole Watsonian angle of playing something in the setting's past as the Doylist angle of giving them a taste of what it was like back when we played 3.5 and 3.P in the setting.

[pabelfly]

I would start them with a basic build, with minimal complex abilities or spells. You'll want to be low-level too, so you don't give them a huge load of complex feats and abilities to master, so I'd start at second or third level (first level can be a bit too swingy to start off with).

If they want to be a mundane, give them a Fighter or Barbarian and do a basic two-hand charging build. Stat out some attack routines for them, like Power Attack 0 and Power Attack 3. Save them the time working it out on their turn and give them a bit of meaningful choice in their build and give them a bit of a taste of when they might choose each option as they play.

If they want to cast spells, give them something like a Warlock, so they can blast all day and not worry about spell slots. Or make something like a Warmage and really simplify the spell list for them.

Once they've had a few sessions to get used to things like movement, attacking, dealing with various modifiers and so forth, ask them if they want to keep their character - perfectly fine - or try something different, in which case you can see if they want to play something a bit more complex and with more options.

[Kurald Galain]

I'd say the main difference is that in 3E, lower-level monsters are a speedbump at best (whereas the design principle of 5E is that lowly goblins still pose a threat to a high-level party). So it would be fun to make a mid-level party and pit them against a squad or small army of kobolds or goblins or something, and let the PCs tear them apart. Heroes against an army is something they'll remember.

[Particle_Man]

There are ways to simplify a bit, while still presenting complexity as options.

Skill ranks are a good example - you can say "Look, you can either spend the skill points on class and cross-class skills in a fairly find-grained manner, *or* you can just max out this many class skills and do the same every time you level up".

And similarly, some feats "do new things" and some feats add pluses to things the characters already can do.

Similarly a character can take the regular class level or they can look at racial substitution levels, alternate class features, etc.

So present the simple options but also allow for complexity where the players want it. The "tinkering" is part of the appeal of 3.x after all.

[Telonius]

3.5 is very, very much more break-able than 5e. And I don't mean in the, "This is overpowered," sense. I mean it in the, "This will actually break your game if you use it," sense.

This is anecdotal, but I think it's apt: about ten minutes ago I saw a thread in the 5e forums about the most damage you can deal in a single hit. Some of the high points were in the 1-2,000 range.

The records for damage in 3.5 are more along the lines of, "All of it." There are combinations that can give you an arbitrarily high strength score, and therefore an arbitrarily high amount of damage. And melee attacks are not really the height of power in 3.5.

I don't have all that much experience in 5e, at all, but I do get the sense that the gap in power between the classes is not nearly as huge as it was in 3.5. You could accidentally build a Druid that overshadows the party. You could build a Monk that's less effective at 20th level than a spellcaster 5 or 6 levels below him.