Finished watching The Quest with my daughter today. Interesting premise, and I think it worked better than I thought it would when I first heard about it.
You don't want to go in thinking you are going to see an epic fantasy story you have never seen before, or even something with clever twists, from a narrative standpoint. The purpose was to do a Survivor-lite series with Lord of the Rings sets and makeup to appear to the folks that like that sort of thing. Personally, I thought it was kind of fun.
It did put me in mind of the gamer lessons to be learned from the show.
1. Having important things for the PCs to do that aren't always combat.
There were a lot of challenges that amounted to preparing for war, training, and building defenses, that if done right, could be fun to do and don't involve direct combat.
That said, I think in some cases, it would be very important to come up with desirable outcomes and let the PCs figure out how to achieve them would be important, to avoid some of the worst variations of WOTC's 4th edition skill challenge missteps.
That said, I love a good in-game tournament.
2. Dealing with monsters way above your normal abilities without fighting them.
There are a couple of challenges where the contestants had to keep monsters from getting out. Giving PCs information on the only place monsters could attack from, at least for a while, and letting them figure out how to seal up or collapse a cavern, for example, seems like a much more satisfying way of letting them take on something outside of their abilities than giving them the "Thing of Slaying" that gives them an excuse to be more powerful than they should be.
Additionally, it keeps them scared of the monster. If they don't seal it up or delay it, they don't have much of a chance to survive it. Giving them enough information to help them outsmart the monster, but also enough to let them know how boned they would be if they tried to stick it with the pointy end would be key.
It also seems like this is a better option to introducing them to the threat of a dragon than, for example, the scenario in Hoard of the Dragon Queen, that gives you conditions for a dragon that should own them running off if they do X in combat.
3. Fallen Heroes in Avalon or Somesuch.
I really kind of like the idea that your fallen companions end up waiting in some version of Avalon, and if the last person standing ends up being "the one," all of your buddies come back and join your army again for the final fight.
Not sure how to pull this off in game, and still have a sense of risk, or so as to avoid handing someone that "lost" a character their old character on top of a presumed new character. Perhaps just some kind of bonus (such as constant Advantage in 5e) that represents them charging in beside you to help.