Industry Advice for Writing Games
1. Humor is a very important part of entertainment. So if you can make it amusing, that's the easiest way to go. Unique abilities are also good. Earthworm Jim's suit would use him to achieve its goals. Funny stuff like that adds spice to the characters you're creating.
2. Somebody once said that a great character has a unique silhouette—if you can identify a character just by its outline, you know you've made something that will stand out in a crowd.
3. Wish fulfillment is the main secret to character (and game) design. Never forget that you're providing players with the chance to do something they can't do in their daily lives. It should be something that they really want to do, if just for a little while.
4. Let the player experience the world through the eyes of the protagonist; if the protagonist's eyes are jaded or all-knowing, it's not particularly interesting. But if the extraordinary things that happen on her journey are as surprising to her as to the player, there's an instant link between the person playing and the character he or she is controlling. And that's a good thing.
5. Break the rules. Game design is full of devotion to stupid conventions that are slavishly copied in hopes of duplicating success. Innovation requires a leap of faith into the void. And that's the easy part.
6. To make great games, you have to know which rules to break.
7. New and interesting weapons are also important. Nothing is worse than playing a game with a leaky peashooter. So great firepower is a good way to pat a gamer on the head.
8. A big secret of superior interactive storytelling is the concept of multiple good outcomes, with varying degrees of "good."
9. Each choice has real consequences and real rewards far beyond issues of death and survival. They take the player along differing paths through the main story, and result in a range of consequences and endings depending on the preponderance of choices made throughout the game. This lets the player feel more in charge of his destiny.
10. It's also important that the player has a sense of why he gets the outcome he did. He doesn't need to understand the direct consequences of each choice, but should have some idea.
11. One of the best ways to offer multiple good options is to use the approach of short-term pain for long-term gain versus short-term gain for long-term pain. Tempt the player with expedient choices, but hint that there's a price to pay later. And offer a price to be paid now for hope of a return later. This is a diabolical bind, and makes for very textured choices for the player—neither of which is obviously objectively bad. When players are wracked with nervous apprehension while making choices, you have done your job.
(c) Marc Saltzman's Game Design: Secrets of the Sages, Third Edition.