Games tend to cycle through motifs, design ideas that somehow filter through multiple games at the same time. At the dawn of the year 2015, on the Chinese zodiac calendar it was Year of the Horse. This turned out to be a fitting moniker for the months to follow.

Players spent hundreds of hours galloping over vast open worlds bigger than any seen before. In a 3DS remake of a Nintendo classic, The Legend of Zelda: Majora's Mask, we saw Link reunited with his beloved Epona in the backward fever dream of Termina. In Bloodborne, haunted carriage rides revealed secrets, and the abandoned corpses of former equines (all, curiously, missing eyeballs) shouted warnings.

We also got to drive horse-drawn carriages around London in Assassin's Creed: Syndicate, although those handled more like sports cars.

I suppose I shouldn't have been surprised, then, when Ocelot came onto my radio in Metal Gear Solid V to chide me about leaving D-Horse, Metal Gear Solid V's equine of choice, behind. I was about five seconds into what I assumed would be a cross-desert sprint, when he asked, What, are you going to run across all of Afghanistan?

Um, yeah; haven't you ever played a videogame before?

"Use your horse, Snake."

As allies, horses in games straddle a line between companions and vehicles. They possess a sense of personality and independence that a stolen car lacks. They allow developers to add nuance to how spatial navigation works: Horses can push back, or pull away, evince an eagerness to explore the open plains or reluctantly climb a steep hill. A well-designed horse is a character as much as it is a mode of transit. In real life, horses have worked alongside people almost as long as we've been domesticating animals, and an equine companion provides games with a chance to dive into the millennia of associations tied into that.

A horse allows a game to re-orient its relationship to its own spaces, setting a deliberate pace and tenor to its navigation: Faster than walking, but slower than a warp zone. Horses also are a means of suggesting an era and location. Horses are metaphors for travel, freedom, and spatial empowerment.

That's what Ocelot was getting at, I think, and I feel it as soon as I hop on D-Horse. He's an eager beast, nearly fast enough to catch a tank rolling down the open Afghani roads. Probably to ease the play experience, he moves a tad unrealistically, turning on a dime and barely balking at uneven terrain. Riding D-Horse in Metal Gear Solid V is an expansion in the scope of the player's efficacy. He offers a small, spry stealth operative the ability to dominate an entire theater of enemy operations. He's the first of a handful of companions the player can find in MGS5, and his presence immediately reorients the player to this new Metal Gear's expansive gamespace. With him at your side, an entire country is yours for the infiltrating.

Roach, Geralt's horse in The Witcher 3: Wild Hunt, is not quite as accommodating. (Fun fact: Geralt names every horse he ever owns "Roach." It's, uh, cute?) You get the feeling that developer CD Projekt Red never quite got the hang of coding a horse that was both realistic and comfortable to use, and as a result, several patches later, Roach is a stubborn, headstrong thing, a wild horse for charting the Continent's vast wildernesses.

One of the most memorable videogame images of 2015, almost on par with 2014's horrifying and hilarious Assassin's Creed: Unity face glitches, is that of Roach coming unmoored from The Witcher 3's textures, skidding over the side of a mountain like a snowboard. Even when he's working correctly, though, he can be difficult to get along with. He offers Geralt the power to travel across the vast space his game offers, but at the cost, occasionally, of the player's patience.

That's what horses in games are about, and why they cast so great a shadow over gaming in 2015. They're about the power to move. They represent an overland method of travel, one slower and more intimate than a car, one fitting fantasy settings and ahistorical wastelands alike. Giving a player a horse suggests a methodical approach to travel, one that favors intimacy with a game's environment without sacrificing freedom of movement, or risking dwarfing the player with its sheer scale.

And scale was certainly one of the defining qualities of gaming in 2015. How many zones are there? Who has the biggest open world? How free am I to explore? Is releasing a short, linear action game even a viable option for a big-budget title anymore? A horse is an answer. Giving a player the chance to saddle up is an invitation to explore the edges of a map, running and running until the ground fades out underfoot.

Even placing horses in the setting, as games like Bloodborne do, offer a symbolic rumination on space: Those dead horses are a promise of confinement as potent as D-Horse's promise of freedom.

A horse as an ally also offers a player a sense that, no matter how far their explorations take them, they'll never be alone. That's the emotional core of Link's connection to Epona in Majora's Mask, and there's a flash in it in the brief views of next year's Wii U The Legend of Zelda that sent fans into a tizzy. No matter how far you travel, giving the player a living companion, one that aids them in getting around the way a horse does, suggests that they can carry a piece of home with them. No matter where you go, a friend is as close as a whistle away.