The June, 1997 issue of "Next Generation" magazine featured an interview with Roberta Williams and Mark Seibert, respectively designer and producer on Sierra's forthcoming King's Quest: Mask of Eternity game. Next Generation:  Do any of the puzzles [in Mask of Eternity] have multiple solutions? Williams:  We thought about doing that but decided not to. Seibert:  When we first started the design, we talked about multiple solutions and multiple paths.  The more we talked about it and the more we researched it, we learned that especially with adventure games only about 13% of the people who play them actually finish them.  [Laughs]  Then it was like, why do we want to make all these multiple paths? Why indeed.  It seems, however, that Seibert and Williams have really missed the boat on what non-linearity in computer games, adventure games in particular, is all about.  Despite the fact that Mask of Eternity is supposed to feature a "hot new 3D engine," it would appear that Williams and Seibert still hope to constrain the player's options to playing one set-in-stone storyline, where there's only one solution - in any given situation - which you're "supposed" to perform.  Any attempts at alternate solutions to given situations, regardless of how clever, will result in failure.  How is this interactive, again?   I feel that the point of computer games, again with adventure games in particular, is to present each player with an experience that is relatively unique to them.  That is to say, the computer reacts to the choices the player makes, and creates an experience that, ideally, only they will have.  Sadly, many story-centric adventure games such as (by present indications) Mask of Eternity, don't really create a gaming experience which is unique to the player.  When different players talk about the adventure game they've both just finished, the difference in their experience will only be where they got stuck in the game, not in how they succeeded at it.  For in order to succeed in the linear adventure game, they must have made the same decisions at each juncture to have finished.  In the end, each player will retell the exact same story of "his" adventures.  Is this interactive? Whaddaya Mean, Non-Linear? Non-linearity doesn't just refer to storylines, it refers to the type of gameplay involved.  In a constrained adventure game such as Mask of Eternity, only one path will lead to success, and only one style of playing the game will allow the player to finish.  It's linear.  In a non-linear game, the player can succeed in many different ways, hopefully enough different ways that each player's gaming experience will be unique to them.  Different types of computer games are non-linear to different degrees and in different ways.   Though the term is most often applied to role-playing or adventure games, arcade games or strategy games are non-linear in their own way.  For instance, in a classic arcade game such as Centipede, each player is able to succeed using different strategies, ones she develops herself while playing the game repeatedly.  The objective remains the same:  to destroy the downward-moving centipedes and other enemies, so as to survive as long as possible while achieving the highest possible score.  Different players will develop different methods to achieve this same end:  some will meticulously shoot at the mushrooms on the play-field so as to maintain an obstruction-free space to survive in, while others will concentrate all their efforts on the moving adversaries on the screen.  Other players still will go for the non-threatening but high-point-earning scorpions which traverse the top of the screen..  Still others will come up with their own strategies for success.  And all these different methods can still lead to a player gaining the highest score at their favorite arcade, hence (in some ways) "winning" Centipede. For all intents and purposes, Damage Incorporated is a sophisticated arcade game, and as such is "non-linear" in that their are multiple strategies that can all lead to success.  Though the objectives vary from level to level, your goal is always to finish the given area so as to progress to the next one, and this primarily involves "eliminating" a lot of "hostiles."  However, this eliminating can be accomplished through many different strategies, with differing levels of success coming with the different tactics.  Some may sacrifice their teammates so as to avoid personal injury, while others keep their squad alive at all costs, dying themselves many times in the process.  Both can still finish the can game. But it Isn't Totally Non-Linear   However, Damage is linear in that you can only play the levels in the order they're assigned to you.  Furthermore, the game can really only "end" two ways:  you die, or you defeat the enemy forces utterly.  Your actions in the game have no actual impact on the storyline that accompanies the levels, and it will always unfold the same way.  In this respect Damage, as well as the entire Marathon series, is extremely linear.  But since the game is primarily an arcade game with a story provided as window dressing, this is somewhat acceptable.  The player has their own unique game playing experience through developing their own strategies for completing the levels.  As such, when two buddies who've both completed the game discuss it, their conversation may go something like this: Liz:  Woah, wasn't that great at the end of Damage Incorporated, when Jeremiah says all that weird stuff? Max:  Yeah, it was, I remember that.  But boy, that last level really was hard though, huh? Liz:  Dude, no way!  I'll tell ya what I did.  I set my teammates on Hold Commands, and then instructed them to....   See, it's easy. Max:  Wow, I never thought of that.  Maybe I should play it again... In this way Damage's non-linearity encourages Max to go play the game again.  But, more important to me, Liz and Max had different experiences playing the game. Whereas Liz rocked through the last level without difficulty, Max got his butt handed to him many times before barely finishing the game.  Max felt less accomplished in his skill and thereby less happy, whereas Liz felt on top of the world since she breezed through the ending so effortlessly. Adventure Games are Another Ball 'o Wax With adventure games, however, making the storyline non-linear is the only thing that will make different players have experiences unique to them.  With a linear storyline the designers force the user to follow, the player's creativity is actually discouraged, as only one solution will work for a given puzzle.  It's very hard to find examples of situations in "real" life which have only one solution:  there's almost always more than one way to accomplish a given goal.  Agreed, some paths may lead to greater degrees of success than others, but they're all solutions nonetheless. A popular way of making adventure games non-linear is to allow the user to approach separate puzzles in whatever order they prefer.  That way, if a user gets stuck on one, he can go on to others, perhaps coming back to the troublesome puzzle later on.  Though the puzzles stay the same and still may only have one solution, at least the player is less likely to get frustrated by one puzzle and forsake the entire game.  Still, is the player really getting a unique experience if they can simply reorder the challenges however they prefer?  In some ways yes, in some ways no.  Technically such a game is non-linear, but really game designers should try to not only allow the player to accomplish different goals in whatever they want, but also allow them to solve those different problems in a variety of different ways. A Good Example, if I Do Say So Myself My own Odyssey - The Legend of Nemesis I feel is a good example of how an adventure game can be non-linear.  Though technically a role-playing game, I consider Odyssey more of an adventure-RPG hybrid, as combat is in many ways downplayed while finding solutions to puzzles is encouraged.  But nearly all the puzzles in Odyssey have multiple solutions.  When the player encounters a group of power-mad priests repressing their parishioners, the player can either sneak about and kill the priests, or she can extinguish the source of their power, neutralizing the priest's control over their followers.  Both eliminate the problem of the priests, but the ramifications of the player's choice has an effect on the storyline of the game. Furthermore, Odyssey allows the player to pursue different problems in whatever order they want, and doesn't even require the player to complete all the puzzles they encounter.  There are three ways to get to the end-game section, and from there different actions will lead to four different endings, all of which have their good and bad points.  In addition the game includes many, many sub-plots which the player can pursue or not at their leisure, depending on how deeply they want to investigate the world presented in Odyssey.  The sub-plots will prove helpful to the player in that they provide him with additional skills and magical items which may make combat easier, but they are by no means necessary to finish the game. In conclusion, the point isn't to see how we can get the player to replay the game, but rather to make each player have their own unique experience.  Furthermore, Mr. Seibert's statistic that only 13% of adventure game players actually finish a given game, points out that maybe the reason they don't finish is that they get stuck on puzzles which have only one solution.  They look at the puzzle and say "well, if this were real life I could easily solve this by using the widget from over here on that."  But since that solution isn't the one the designer had in mind, and since the designer didn't bother to take into account the player's creativity so as to allow for multiple solutions to puzzles, the player gets frustrated and quits.  Self fulfilling prophecy, anyone? This column was originally printed in Inside Mac Games.