Videogames, like all forms of media, have their own comfort zones. Themes and motifs that developers can return to time and time again.

This can make for boring, repetitive games, but it can also be used well. Using a familiar theme can draw the player in and allow the developer to play on their expectations to deliver unexpected shocks.

These themes are at once general and specific. They have unique traits that remain constant throughout most of their uses, but also have plenty of scope for developers to experiment and to differentiate themselves.

Take ninjas for example, an ever-popular game theme.

Games like the Tenchu series epitomise this with that feudal Japanese setting and gameplay revolving around stealth. Players must stick to the shadows, using silent weapons, poison, assassination, disguise and distraction techniques to reach their primary target. And, when it comes to a fight, slight and elegant fighting with a trusty katana.

But the ninja theme also encompasses the more brawly, action-platformer series Ninja Gaiden. Infamous for its difficulty, Ninja Gaiden focuses less on stealth and more on fast-paced, violent action.

And yet it doesn’t lose that ninja feeling.

The real strength of themes like these are their ability to permeate other media, other forms of culture, and in doing so appeal to a far wider audience than other games might be able to. Everything and anything from movies to Ninja Casino. When it comes to the big hitters in the console world especially, it’s this potential for cross-branding that comes to the fore.

The military theme is, of course, another that’s prevalent in gaming.

In fact, it’s become so strongly represented by the Call of Duty series that we could almost call Call of Duty a theme in itself. When you pick up a Call of Duty game or one like it (such as Medal of Honor), you know what you’re getting. It’s a dependable theme that players know will bring certain aspects to the table.

It’s going to involve guns and therefore sharpshooting players will find plenty to sink their teeth into. It’s going to involve brutal war scenes. There will be comradery, tragedy, heroism, and fast-paced, quick-twitch action. This makes it dependable within the games industry in terms of a return on investment.

But this isn’t just a cold, calculated ploy for money that results in a soulless. Developers can use these themes as just the baseline for their games, but then vary wildly on the theme. Dependable, tried and tested motifs like military heroism in games like Call of Duty can woo over investors with promise of return. They can then do pretty much what they like.

Two other hugely successful Xbox series, for instance, are Gears of War and Halo.

Now, who could accuse Call of Duty, Halo, and Gear of War of being clones of each other? They all play on the same themes – army hard men, heroic deeds, a great threat and real comradery – and yet all feel like completely different games, completely different worlds. In fact, they are different games, worlds, stories, characters, emotions.

Call of Duty shows us the more traditional take on war. Most of the games are at least loosely based on either historical or current wars, with exceptions of course. It shows a relatable, human side to the topic as we imagine ourselves in the squad, fighting our way through battered and derelict towns.

Indeed, with the ever-popular zombie mode, Call of Duty also does an excellent job of merging with another popular videogame and movie theme, seamlessly yet self-consciously drawing it into its world.

Halo takes us far into the future. The scale of the war is galactical, the enemies a diverse array of alien and the technology advanced but still visceral. It gives us a glimpse into where technology might take warfare. Gears of War also takes us to the future, but it’s a bit more steampunk. It’s gritty, bloody, brutal. The men are grizzled hulks and the enemies Lovecraftian horrors who we love to watch get massacred by chainsaws.

But their commonalities make them familiar and dependable in particular ways, and that allows developers to convince investors that it’s a safe bet, in turn allowing them to make the game they really want to make.

These kinds of themes don’t need to be prescriptive or restrictive. They can be, but only in the hands of unimaginative development teams. Whether its zombies or war, pirates or ninjas, medieval knights or Vikings, what matters is what the developers make of it.