Sequels focused on continuing a story started in the original can be uniquely challenging. Freed of the need to introduce world and characters the focus shifts to expanding the world, and a deeper exploration of the central themes. Providing a bigger context, a broader canvas, on which to explore the escalating consequences of the actions of the characters.
In The Godfather Part II we see Michael Corleone attempting to expand the operations of the family, while dealing with the choices made previously by himself and his father Vito. The continuing themes of family and respect are weaved throughout along with several references both direct and metaphorical to events from the first film; the final scenes strongly echoing the ending of the original in both tone and content.
The goal of such a sequel is one of expansion and escalation, the problems are larger, the stakes higher; to put it another way everything is “Bigger, Better, More Badass”.
This is seen in numerous game sequels, players are provided with larger locations to visit, more powerful tools to wield, and tougher challenges to face. The problems are bigger and so are the solutions.
In Half-Life the initial goal is to escape the Black Mesa Research Facility, there are detours, and the eventual goal becomes something greater but the story is essentially confined to Black Mesa. Escape from the facility comes only at the conclusion. From the very first moments of Half-Life 2 it’s explicitly clear that you will no longer be restricted to the confines of Black Mesa, the world has expanded and you are no longer solely concerned with self-preservation.
The Half-Life series also serves to highlight an inherent character development problem with game sequels. By the conclusion of the original game the player character will have faced and surmounted numerous challenges, often learning new skills and acquired tools and weapons along the way. They end the game a more competent more powerful character than they began it. In order to repeat this sense of character development and progression in the sequel players will be stripped of their acquired skills and abilities. Just how many times does Gordon Freeman have to lose his weapons, just so that they can be carefully portioned back out?
What purpose is served by developing a character when they are fated to lose all progression the next time they appear? Would audiences have accepted The Godfather Part 2 if Michael Corleone was no longer the Don but had to earn that position all over again?
One way to mitigate this is to treat sequels in an episodic fashion with only the most basic of story elements carried forward into each subsequent title. The Tomb Raider games use this approach, until their recent revival, each title was a self contained story with only the barest links to the previous games. Such an approach allows for recurring characters and themes to provide a sense of continuity, while not requiring an extensive knowledge of the back story that might be off putting to new players.
Some sequels sidestep the issue by developing the story around a different protagonist. While avoiding the previous problems such games still need to spent time reestablishing the rules and underlying context for the world. Attempts are often made to tie the actions of the new protagonist to those of their predecessor, such as in Fallout 2. In these cases the overarching storyline is not so much that of either protagonist but the world itself.
An interesting twist on this is the approach taken by System Shock 2, and more recently F.E.A.R. 2: Project Origin, that of a new protagonist but a returning antagonist. Set some forty two years after the events on Citadel Station System Shock 2 features a new blank slate avatar who once again has to deal with the machinations of SHODAN. The story of System Shock is not really the story of the player at all, it is her story. This bring us back to a variation on the original problem; does SHODAN’s reappearance in System Shock 2 serve to invalidate the actions of the mysterious hacker, the player character of the original System Shock? The SHODAN found on Tau Ceti V only exists because of your actions in the original game but doesn’t her very survival call into question the value of your original success?
The beginning of Alien 3 changes the entire tenor of the final sequences of Aliens, as going back and watching it again we know that some of those characters are destined to die. Is the assumption that players are unlikely to revisit the original game so anything is fair, even turning what was once a success into a failure?
The structure of games based on progression from a state of powerlessness to a state of empowerment seems at odds with the desire to continue a story arc; any progression in the first game is immediately negated for the start of the sequel in order for the cycle to begin anew.