Designing the main flow of a game is an important first step to creating a game. However, as the saying goes the devil is in the details. We know how a player is going to win or lose, but what does each individual turn look like? What actions do players take to get eliminated/eliminate players or gain points/resources? How do we make sure each player has a fair chance?
In
Survivor, we know that every round of the game, one player is eliminated. But it would be a terribly boring show if it was just a bunch of people talking. And how would they decide who should be eliminated? This is where the challenges come in to play. Challenges expose the weak and strong players, it chooses which team must lose a player, and it gives the audience something exciting to watch. There are two tricky obstacles the designers of Survivor had to overcome. If the game was individual competition the entire time, that would be almost as bad as not having challenges since players wouldn't have too much information on who to eliminate. Secondly, they cast people from all walks of life, so they have to have some way to make the competition fair between man and woman, nerd and jock, country and city dweller.
One solution to both of these problems is to have the first half of the competition be team oriented and the second half be individuals competing. This means strong players can make up for the weak players. Weak players can be blamed for losses. But they can't just always eliminate the weak players because at some point, they will have to compete with individuals and being up against weak players at that point is crucial to winning immunity.
But if that was the only solution, then poorly made teams would make for a bad season. The other solution is in the individual design of the challenges themselves. Early on, all competitions are either relays or turn based games. The relays always have at least two parts: a physical component and a mental component. A race to collect puzzle pieces and solving the puzzle. This lets teams divide their strong physical players and their strong mental players (and the trouble lies in if they only have one and not the other). The turn based games (shooting a coconut slingshot at a wall of tiles, a variant of basketball with three players of each team at a time, etc.) are all designed so it's near impossible for a single player to do so poorly that they make the team lose. Just because you missed the shot once doesn't mean everyone else is forgiven for also missing their shots.
Once the competition is slim enough to go to individual competition, they alternate between challenges from one of the following categories: strength (races), endurance (keep a ball on a platform for as long as you can), mental (puzzles), social/knowledge (trivia about what other players have said). This variety once again makes it very difficult for one player to dominate and keep gaining immunity. It doesn't make it impossible, but if that super strong player EVER loses a challenge, you can pretty much bet they will be eliminated.
The best way to balance any game and keep it fair for all players is to have that balance built in to the game. Whether this is through a variety of ways players can excel (in Settlers you can build more settlements, upgrade existing settlements, or use certain development cards to earn points), giving everyone an even chance of success despite skill (everyone has the same chance of drawing a high card in War), using groups (you can still win Pictionary if you aren't good at guessing as long as others on your team are), or some other way you can come up with. The more built in balance a game has, the less you have to work at shifting numbers and probabilities to keep your game fair.