Ooh, what kind of board game? 
I don't think people who haven't played the earlier games can really understand; it's a work of fan fiction that doesn't make sense when taken out of context. It caters specifically to KQ fans by bringing in characters we've met and loved in past gaming experiences. People who haven't had those won't be touched in the same way.
What kind? Well, the goal is: You (and whomever else is playing with you) have been captured onto an alien ship, and thanks to a very convenient temporary power outage from passing by a solar flare, have broken out of the Brig and try to make your escape. Unfortunately, this temporary power outage both helps and hinders you. Why? Because, not only have you gotten out, but also all the robots and various experiments are running around rampant in the ship!
Your goal is to reach the Bridge, where the Captain Great Cthulhu awaits you and when you defeat him, you need to reach the escape pod.
This game involves a LOT of dice (twenty sided and six sided), and a LOT of lucky rolls along with them. I felt so sorry for Dennis (one of our teammates), because he was doing so well in the beginning... and then he fought the Head of Security, got him down to 5 health and then Albert stepped in and not only killed the boss, but stole the item he dropped too because he got a higher roll!
Then, things just went south for him, as he was getting event space after event space and had to keep fighting and fighting and getting beat up, and when he finally reached the Medical Bay it got worse. Why? Because like everything else, it depends on your roll. Roll a 5 or lower, you hurt yourself for 5 damage (and he had 6 health and a maximum of 20). Roll between 6 and 18, you heal yourself completely. Roll between 19 and 20, you heal yourself completely AND increase your maximum health by 50%. Dennis got, like, 4 on his die and hurt himself for 5 damage. Now, he has 1 HP left and is considering just giving up. He goes outside the Medical Bay, lands on an event space... and the Event Card that says "A Security Turret spots you on its radar and ZAPs you! You lose 1 HP!" and died instantly!
"Oh come on! That's like coming out of the hospital and getting run over by the ambulance!"
I was tempted to make a Space Quet reference, since his bad luck reminded me of all the nasty ways Roger could die.
In contrast to me, who was doing GREAT up until the very end: I got the BFG amongst other weapons I don't remember, had barely lost any HP at all, managed to kill the Weapons Master (the one boss guarding the Armory) IN ONE HIT by getting a roll of 20, AND I was the one who killed Cthulhu IIRC... and then I ended up tripping over my own clumsy feet (as I said) by getting a roll of 6 (three six sided dice all of them rolled on 2) when I need 9 to reach the escape pod. In fact, the only one who made it was Albert, the one who as Dennis quoted was "The one who rode on everyone's coat tails." although, Albert didn't agree with that statement.
All in all a very fun game, but very much based on luck.
As for TSL, that's the thing. I TRIED to explain the backstory to him (about Graham, his family, and trying to summarize each game), including the significance of the Black Cloaks... but he just didn't care about any of that.
I told him to give it a chance since it has a great story and great characters (thanks to, of course Katie and Cezar I assume), but he told me, "If I want that, I'll read Isaac Asimov, Terry Pratchett enc..."
People who haven't played the earlier games? Um... what about me? I haven't picked up ANY of the KQ games, and have only knowledge of them through various Let's Plays (Paw, Dilandau3000, hercrabbiness enc), Paw's Retrospective (how I found out in the first place what KQ is), TV Tropes, the King's Quest Omnipedia and this site. The only games I've ever picked up are the AGD remakes of 1, 2 and 3 (but after seeing a couple Ways To Die videos on IA's version of 3, I will probably never pick up that. I think it's the graphics and voice acting that get to me, especially since I was introduced to AGDI' version first.)
I haven't played ANY of the official games, and yet I love The Silver Lining regardless! I didn't even know what King's Quest really was (aside from "It's an old brutal game from Sierra!" whispered about on TV Tropes) up until last year.
Yet, you guys accepted me here regardless.