They won’t know at least one of the character, the setting or the system. If you’re unlucky they won’t know all three. Even if you had stuff ready prior to the first session and the player took it, you can’t count on them actually taking it in. In a campaign game, you have time to interact with and educate a player on what they missed.
The players aren’t being difficult. Within a con game, the players are in the middle of a period of extended concentration. They have to pick up multiple new concepts and link them together time after time after time. Not only that, but there is a very good chance that they are tired as well. Con fugue sets in (sometimes quite early in the piece). Or time they anticipated reading your stuff got eaten with an overrun session. Lastly, some players have difficulty taking in any information via a written format.
You carefully prepare your system and setting notes for people who don’t know the system and setting. You offer characters early so players can read and absorb them prior to setting foot in the con. Unless you are very lucky to get that team in their first session, they still would have had other games to think about, overwriting what information they absorbed.
Possibly I’m exaggerating in saying players will forget it all. Most likely, they will remember bits and pieces of what you’ve written. But this might mean that they don’t notice they have forgotten that one vital clue/character trait/rule which clinches the game.
There are a couple of approaches which have been tried over the years to overcome this particular issue.
- Offer stuff beforehand - Yep, it’s been tried. As you can see, it’s not one I’m a fan of.
- If it’s important, put it down in ways the player can’t miss. Repeat it, or provide a dot point summary.
- Write it short and sweet – The art of editing. Mark Twain’s quote “I didn't have time to write a short letter, so I wrote a long one instead” shows that crafting something succinct can be more skilful than going on at length.
- Use a different format – Tell them or show them instead.
The last thing to remember is that no matter what you do, players won’t get something. You have to count on players forgetting a piece of information during play for all the reasons above, no matter what you do. If it happens, I suggest considering whether it’s a game changing piece of information. If it’s not, maybe leave it alone? If it is, one possibility is that they have a different understanding of the character, rule or setting they are about to use. The other is that they have forgotten that aspect. I’d suggest checking in with them.