The following is text from the "Big Eyes Small Mouth d20", second edition revised (copyright 2004). This is selected text which reveals the authors' view of what roleplaying is and the responsibilities of GM and players.
"ROLE-PLAYING GAME MANIFESTO" Section, page 2
These rules are written on paper, not etched in stone tablets.
Rules are suggested guidelines, not required edicts.
If the rules don't say you can't do something, you can. There are no official answers, only official opinions.
When dice conflict with the story, the story always wins.
Min/Maxing and Munchkinism aren't problems with the game; they're problems with the player.
The Game Master has full discretionary power over the game.
The Game Master always works with, not against, the players.
A game that is not fun is no longer a game -- it's a chore.
This book contains the answers to all things.
When the above does not apply, make it up.
"WHAT IS ROLE-PLAYING GAME?" Section, page 6
For many people, a role-playing game (RPG) is the “mature” version of the games we used to play as children: “House,” “Cops and Robbers,” and “Superheroes.” A rule system assists in settling conflicts and resolving actions, often with the use of a random generator (usually dice) to add an unpredictable element to the game. A game requires a handful of players and one person to act as the Game Master (GM) or referee. The players tell the GM what their anime alter-egos would like to do, and the GM describes the results of their actions. The GM is also responsible for creating the plot and the setting for the game adventures and works closely with the players to keep the game interesting and fun for all.
In Big Eyes, Small Mouth d20 (BESM d20), players assume the role of an anime character suitable to the time period and setting of the adventure the GM will be using. The game system helps players assign some strengths and weaknesses to their characters using numbers to indicate relative ability. The remaining elements of a character's background, family, hobbies, and interests are not covered by the rules and are described by each player according to his or her choice of character personality.
As a player, you control your character's actions in the game. He or she can be likened to one of the major characters in an anime movie, working through the unexpected twists and turns of the plot with the help of other major characters. Your character's actions can greatly affect the outcome of the adventure, but you must keep in mind that every action has a consequence that could return to haunt your character in a future session. Role-playing is a group effort, however, and positive interactions between your character and those of the other players are vital to everyone's enjoyment of the game.
As a GM, your contribution will be much greater than that from any one player. You must establish the genre, setting, conflicts, and plot of the adventure as well as all the non-player characters (NPCs) your group of players will meet during the game. NPCs are similar to the background characters in a movie -- few are given quality screen time with the major characters unless they are good buddies, or central to the plot. Additionally, you must be able to project your imagination to the players by describing in vivid detail the world in which they live. Then, after all that, your game plot must remain sufficiently flexible to allow the characters' actions to make a definite impact on the adventure. A plot that is too rigid may leave players feeling their characters have lost the free will to affect their own destiny. Should you assume the role of GM, you must possess creativity, good judgement, and the ability to improvise in unexpected situations. It takes extra time and effort, but the reward of a well-played adventure can be almost euphoric.
Each role-playing adventure or episode will require one or two sessions, each several hours in length. A number of episodes using the same characters can be linked together to form an anime campaign. Campaigns require more commitment from everyone involved, but watching the characters grow as the greater plot unfolds makes the extra effort worthwhile. The most engaging campaigns can last upwards of 5-10 years, but keeping a campaign running for 8 months to a few years is considered tremendously successful.