Moving games into the third dimension introduced a new challenge for game designers: player-controlled perspective, and the host of problems associated with it. One of those problems is guiding the player’s eye. How can you direct them toward the next objective? How can you make them notice special events and clues? How can you ensure that they’re facing the right direction at the right time?

Michel McBride-Charpentier explored some of these methods in a post entitled How Designers Turn Heads. The most naive solution is to “simply temporarily remove camera control from the player and send it off somewhere with a script”, a blunt method which sacrifices player immersion and denies the interactive nature of games. A step above this is the Gears of War approach, where “the camera can be focused on a special event at the press of a button.” This offers the player a simple binary choice: look at the event or ignore it. This method is still artificial and inelegant, as it relies on a “giant blinking controller button prompt” to indicate that something is happening.

The best approach is to guide the player organically, catching their eye with elements that fit seamlessly into the game world. In this school of thought, Valve is peerless. The Half Life series is a testament to subtly managing the player’s navigation while maintaining the illusion of a big open world. I’d like to explore some of the methods they use to do this, using screenshots from my recent playthrough of Half-Life 2: Episode Two.

Flock of Birds

One of the most obvious tricks that Valve uses is having the player startle a flock of birds which fly off in the direction of a distant object of interest. Their sudden movement captures and directs the player’s attention. As Michel put it, “Birds are never just birds in Half-Life 2.”

For instance, near the beginning of the game, the player approaches a cliff overlooking a small abandoned factory and startles a group of crows1.

As the birds take off, they fly toward a rooftop where the player can catch a glimpse of a Hunter robot stalking them. This neatly foreshadows the upcoming encounter.

Getting the player to look at the birds can also be inherently useful. Valve occasionally uses them as a proxy for the player, demonstrating the consequences of nearby danger.

Halfway through “Under The Radar”, the player has been tasked with taking out the Autoguns that are defending a nearby Combine bunker. As the player crouches to enter their firing range, he/she startles a nearby crow.2

The Autoguns swiftly target and dispatch the bird, warning the player that they must remained crouched in this area or suffer a similar fate.

Ammo & Supplies

Another method that Valve uses to draw the player’s attention is the careful positioning of supply crates. In many first person shooter games, unmarked crates and barrels may or may not hold health and ammo. The player must therefore break everything in sight in order to replenish their supplies. In Half Life 2, however, ammo caches are clearly identified by a yellow marking. The player will therefore consciously look out for them and navigate toward them.

For example, halfway through the Antlion den, the player spots a yellow ammo crate sitting in front of a wooden plank wall.

On approach, an Antlion Guardian breaks through the barricade and attempts to slash the player. This prompts the Vortigaunt companion to comment on this new enemy, and once again foreshadows a future confrontation.

In another example, a shield battery can be seen next to a fallen ally at the end of a dark hallway. This encourages the player to investigate the corridor.

At the end of the passage, the player finds a hole in the floor. The presence of additional health and shield supplies at the bottom indicates that the player should jump in and explore it. Like breadcrumbs, the path through the following underground tunnel is also marked by scattered supplies.

By using supply caches as navigational tools, Valve provides game world incentives for staying on the right path. Furthermore, since they disappear after being picked up, ammo and health provide one-directional guidance. There’s little chance of the player inadvertently following the chain of supplies backwards.

Barnacles

Barnacles are passive ceiling-dwelling enemies. They drop down a long sticky tongue that latches on to anything it touches, pulling up prey to their razor-sharp mouth. They’re used in many creative ways in Half Life‘s level design, including inciting the player to look straight up.

For instance, toward the end of “This Vortal Coil”, the player walks into a cavern where a Barnacle’s long tongue is hanging down.

The player looks upwards to kill the enemy, only to discover a web cache with health and ammo embedded in the ceiling. Had the Barnacle not directed the player’s attention, the concealed supplies would likely have gone completely unnoticed.

Graffiti

Finally, Valve will occasionally make use of suggestive graffiti to lead the player’s eye. This approach is a bit lacking in subtlety; why would anyone tag a wall with lines and arrows? Fortunately, it’s a technique that’s used sparingly.

The shed that houses the Autoguns features some suspicious markings, possibly tagged by someone named “Mooee”?3

Turning the corner, the player finds a Zombine hammering on the back door. This communicates that the door is locked, and that the player should seek an alternate entrance.

Valve subtly guides the player’s attention toward significant events and objects by using elements naturally found in the game world. This allows the player to retain control of their perspective without getting lost or confused, and contributes to an overall immersive experience.