I think every table has at least the occasional player who doesn’t read or doesn’t quite grasp what’s written in the rulebooks. I’ve occasionally been that player.

I think it’s worth it to talk to them specifically about the issue but don’t be a hard-ass about it, this is all supposed to be for fun after all. Don’t just suggest “read the book” because to some people that’s basically just saying “here, read this text book” suggest the specifics parts the need to brush up on.

Maybe suggest they make, or just make one for them, a cheat sheet with the necessary info on it that they keep forgetting, depending on what they need it could just be some notes scrawled in the margins or on the back of his character sheet, or maybe a separate print-out or some flash cards.

Of it’s a general issue with the players forgetting rule, talk to them about switching systems. I wouldn’t play Pathfinder 1e for example with a very casual or rp focused group. There are so many systems that do exactly what we want on different levels of crunch. If you need recommendations you can ask in this group, but talk to your players. This works especially when your players don’t care about the system you play.

Other than that, there are a ton of cheat sheets for how mechanics work online, to print out.

Hope I could kinda help

Depends on the casualness of the group.

Pick-up games, almost nobody knows the rules. Don’t use complex games with them, use tiny little indie games instead. Get an OSR game like Knave, and it’s almost impossible to not understand the game.

Longer-term groups, I do expect everyone to read the rules, and using more complex games is fine. Someone who won’t, and especially if they picked a more complex class or skills, needs to read the book, change characters, or go to another group.

For a quick one-shot to test out the system, most of my players will just skim the rules, and that’ll be enough. But if I run a long-term campaign I expect my players to have a basic grasp of the rules, but most importantly know how their characters rules works.

I will happily explain and help players get started. But if they ask me for 100th time which die to roll; don’t know how their character works; or similar basic things, I will get pissed at some point and ask them to please learn the game we’re playing.

You don’t need to know every single rule, but a basic grasp of them is just the bare minimum or I will kick them out of the game at some point. This hasn’t happened to me yet, all my players are very good at picking up new systems.

I let the rule-book on the PC side of the table, and expect that player get at least a basic understanding of the rules, especially if they have special power (Like spells/psy/cyberware).

That said, if players struggle to understand the rules, may-be it’s also an issue with the game

I wouldn’t require players to read the whole rulebook or books. However I expect players to know the basic rules that come up all the time after a while. Also I expect players to know what their spells and abilities do and have the page numbers noted on their character sheet/pdf/whatever next to the ability for easy referencing. This is something I make very clear during session zero. There is some learning by doing and there is some reading up you need to do.

In return players can expect me to know all the rules which I expect to be relevant during a session (e.g. if there will likely be underwater combat I’ll make sure I refresh my knowledge on that). As a GM I will make sure I know the spells and abilities of all enemies and monsters I use and how they might interact with the PCs. I’ll also have page numbers for rules, spells and monsters ready if things get unclear.

I’ve played with two groups, and everyone has figured out how to handle their class features.

I think it’s worth a chat with the players.

In my experience my players are excited about the rules and how their characters work - but not all of them learn well from “just reading the rules”, like it literally does not stick. Just telling them to read the rules isn’t going to do anything but make them feel shitty about the game.

Talk to your players about how to help them remember or have easy access to these rules. Make sure you don’t get too accusatory, you do want to play with these people after all.