Anatomy of a 2D Sidescroller Luis Barriga
Before we start • Please turn off cell-phones and pagers. • Save your questions for Q&A after lecture. • Turn in feedback forms before you leave.
Introduction • Purpose of Lecture • Establish that 2D is a format and not a technology limitation. • Propose the analysis of 2D games as a tool for understanding universal gameplay fundamentals. • Dissect the common components of 2D games as well as their evolution throughout time.
Lecture at a glance • On having more D’s • Elements of a 2D sidescroller • 10 Model games
On having more D’s • 2D as a technological limitation • Immersion vs. abstraction • Ambiguity in representing 3D in 2D media • 2D and 3D as presentation formats
On having more D’s • 2D as a technological limitation • Since the mid-90’s, 3D has been seen as an improvement over 2D. “The next step” • 3D capable platforms are more technologically advanced, thus not using 3D is often seen as a “waste.” • Even in very 2-d specific platforms, rudimentary 3d engines are often seen as a tool for differentiation.
On having more D’s • Immersion vs. abstraction
Immersion vs abstraction • We experience the real world in 3d • We communicate abstractions in 2d • Letters • Maps • Symbols • Charts • Diagrams
Immersion vs abstraction • Spatial perception • The ability to mentally model/manipulate 3D images. • A skill that human beings develop over time (and are even tested on), it is a factor that must be considered when designing a game An example of a spatial perception test taken from http://www.exn.ca/brain/tests/
Immersion vs abstraction • A thought on gender • Psychologists have found that males have an advantage at spatial perception and object displacement. Even about finding their way around maps. • They’ve also found that females have an advantage at remembering landmarks. • I am not a psychologist. http://www.unn.ac.uk/academic/ss/psychology/resource/py095/LECTURE7.HTM http://www.psychology.mcmaster.ca/3l03sun/2000-2001W/spatial/0_Group_Game_FinalReport2.htm http://psychology.unn.ac.uk/nick/HPlec06.htm
On having more D’s • Ambiguity in representing 3D in 2D media
Ambiguity in representing 3D in 2D • Technology impediment • Unless a less ambiguous 3d medium becomes commonplace (VR goggles, Star Wars’ Dejarik chesslike holographic display), the “tightness” of gameplay will not be the same in 3D as 2D. • To compensate games must often add a lot more room for error, snapping or automatic guidance.
Ambiguity in representing 3D in 2D • Format difficulties • Making sure objects are recognizable at any angle • Mediation (Camera) issues (3rd person for example)
On having more D’s • 2D and 3D as presentation formats • We should start looking at 3D vs 2D as a choice of formats that will enhance different types of gameplay. • 3D -> Immersion • 2D -> Abstraction + pixel level accuracy
On having more D’s • 2D and 3D as presentation formats • Quite a few games have been pursued a 2D presentation on 3D platforms • Castlevania: Symphony of the night • Viewtiful Joe • Contra: Shattered Soldier • R-type Final • And more are sure to come ;-)
Elements of a 2D sidescroller • The character • The environment • Game objects • Game rules • Mediation
Elements of a 2D sidescroller • Note • Although we can dissect sidescrollers into components, more often than not elements are designed in parallel. For example: designing a grappling hook toss also requires designing environment types that enable this move.
Elements of a 2D sidescroller • The character • From a gameplay standpoint here’s what interests us about the character: • Set of available actions • Visual footprint: shape/size, its visibility and its ratio to the screen and other objects
Elements of a 2D sidescroller • Action sets • Interactivity is the core of what defines games: “what do you do in the game?” vs “what is the movie about?” • Game characters are defined as much by their available actions as by the character’s looks.
Elements of a 2D sidescroller • Example: • I can shoot beams and missiles • I roll into a ball • I can freeze enemies to use them as platforms • Metroid’s Samus Aran
Designing Action Sets • Actions types • Generic (running, jumping, attacking) • Game-specific • Conventions • With a genre as well explored as side-scrollers, many actions have conventions associated with them • Feel free to ignore or work outside conventions but do so consciously (especially with core actions)
Designing Action Sets • Example: Jumping • Pre-scroller fixed jump • Variable jump
Jumping Conventions • Button Assignment • B is action, A is jump • Variable jumping, Y • 2-tier jump • Gravity delay • Velocity reset (direct control feel) • Variable jumping, X • Direct control (character moves when directed) • Indirect control (changes acceleration)
Running Conventions • Mainstream controls don’t always become conventions • Example 1: holding action button for running (Mario games) • Double tap d-pad became convention • In modern games shoulder button became convention • Example 2: Up + Action button for secondary action (Ninja Gaiden, Castlevania)
Damage conventions • Touch damage model • Character takes damage whenever coming in contact with enemy (regardless of whether the enemy is attacking or not) • Brawler model • Characters only deal damage when attacking • Intermediate models • Shinobi, Kung Fu, others. Touching an opponent leads to either mutual repulsion with no damage or a “captured” state with slow damage.
Designing Action Sets • Game-specific actions • Refer to the greater vision or theme of the game to come up with suitable actions. • Bruce Lee: Formidable fighting and acrobatic prowess -> deep combo tree, wall flip, pole slide, etc. • Brother Bear: Animal vs. Nature -> Water sliding, balancing on logs.
Visuals • Shape • Visibility • Size ratio
Visuals • Mental models and Game Engines • Characters in collision engines are usually represented as a box or collections of boxes • The player will develop his/her own mental model for the way the game world works. • A good correlation between the two will lead to a feeling of “tightness” in gameplay • A disconnection in the two will lead to sloppy gameplay.
Visuals • Visibility • Player characters need to be distinguishable not just from the background but also from all other game objects. • Player characters actions and reactions need to be distinguishable from each other.
Visuals • Size Ratio • The size of a character cannot be judged in an isolated manner. • We need to consider the ratio of a character’s size to: • The screen • The character’s actions’ visual footprints • Other objects
Size Ratio – vs Screen • A screen must fit: • A character centered roughly on the bottom leftmost third of the screen. • A character’s full jump arc • A complete or near-complete encounter • Example: a bare pit must have both of its ledges visible. A pit with an enemy threatening one of the ledges must also account for the enemy’s patrol range. • HUD and so on.
Size Ratio – vs Actions • Ratio vs Jump • Jumps are usually tall enough to clear at least one character unit (so you can jump over equivalent enemies). • Jump should be small enough to not exceed the screen size of a centered character as it’s a convention to lock the camera through the natural arc of a jump.
Size Ratio – vs Actions • Ratio vs. Attacks • Aim for your attacks to extend at least around one character unit out.
Environment • The Environment • The environment can only be analyzed within the context of handling. • A Mario level will play very differently with Spider-man as a player character.
Environment • Building levels • There are many approaches to building levels. • It’s always good to prototype a level before dedicating art to it. • Building metrics. The character’s actions imply metrics, good levels take these into account.
Building levels (continued) • Build encounters • Encounters are group of environment sections and game objects that need to be considered by the player in conjunction • Once an encounter works, use it as a building block.
Building levels (continued) • Build a narrative • Sometimes you just have a strong vision of “moments” of gameplay. • In these cases linking these in a narrative form and translating the narrative into a level works well.
Building levels (continued) • Example: • Bears sliding down waterslide. • Bears getting shot off the end of the waterslide. • Bears landing directly into a balancing act position. • This led me to design a level where you slide down a long section, avoiding rocks, collecting berries, get shot off the end of the waterslide and landed on a log.
Character Character Character Building levels (continued) • Metrics
Building levels (continued) • Jump Metrics • Jump height • Jump reach • Jump width • Other Metrics • Landing space • Crawl space