This is what happens when you add the Macho Man Randy Savage to "Skyrim." FancyPantz

One major advantage of playing video games on computers instead of game consoles is the ability to mess with the structure, look, and gameplay of your favorite titles.

This is known as "modding."

"Modding" is just jargon for "modifying" – altering – video games. Savvy fans dive into the back-end of their favorite games to fix bugs, update graphics, or introduce new elements. Sometimes, fans create new games altogether (we're looking at you, "DOTA"). Some game studios create custom "mod tools" for their games, making the process even easier for the less code-minded among us. In order to play a mod – even ones that are essentially full games – you need the underlying game on your computer. The mod runs on top of the original game. Think of the original game as the foundation. The mod is the house built on top of that foundation.

Video game players have been mucking about on the back-end of popular titles – from "Skyrim" to the earliest text-based adventures – for as long as games have been on the market. And, for nearly as long, those edits have passed back and forth on the internet.

Nowadays, it's thankfully much easier to install these mods: it's as simple as downloading a file and installing it. By far the best and largest source of mods is the Steam Community Workshop, which gathers, gives out, and sometimes sells player creations. And it does so within the confines of the world's largest, most popular digital game store: Steam, which boasts over 100 million active users.

Most mods just add items or characters to games, and many fix bugs. But others are deeply weird. Some people can only play a character for so long before wondering "What would it look like with a hamburger for a head?" or "Why doesn't its gun fire rainbows instead of bullets?"

Take this image, for instance:

This is what happens when you add the Macho Man Randy Savage to "Skyrim." FancyPantz

Someone took a look at the dragons of the "Skyrim" universe and thought, "You know what those things are missing? The hair, voice, and headgear of WWE superstar Macho Man Randy Savage." I don't care if you're miles from WiFi, reading on your last megabyte of data. The video below of a freakish wrestler-dragon hybrid attacking a town is worth the watch:

The amazing thing about that clip isn't just that someone had that idea; It's that they took the time to meticulously and expertly patch it into the actual game.

Modding goes much deeper than bizzare aesthetic changes or new characters. Some creative (and invested) fans have modded games to entirely supplant their original worlds.

"Black Mesa" is one of the more ambitious examples. It takes the classic 1999 "Half-Life" game and entirely rebuilds it from the ground up with better graphics and smoother gameplay. The Surface Tension level in "Half Life." Valve The Surface Tension level in "Black Mesa." See the difference? Valve Check out the images to the right to see for yourself.

At its core it's the same game. Modern graphics, new items and dialog, redone music and voice acting combine to make it play like a modern release.

A few levels of the mod came out in 2012; The rest will arrive on Steam sometime in the future. (Like the "Half-Life" series that gave it life, "Black Mesa" is famously plagued with delays.)

But mods can do a lot more than just modernize a game. Mods can transform an old title into something entirely new and far better.

Take "DayZ," a game that began its life as a mod of the 2009 title "ARMA 2."

"ARMA" is a series with dedicated fans, and it's not intended as a blockbuster. You won't see it at your local Best Buy, or see commercials alongside major NFL games. It's a niche game with a niche, loyal following. All that to say, "You probably don't need to play it today." It's highly technical and not always the most "fun," in the purest sense of the word.

"DayZ" is something else entirely.

Despite its status as a patch on existing game, it was (and, in my opinion, remains) the best "survival" game ever released. That genre, which "DayZ" largely invented, puts players in the position of fending for themselves in a hostile world, working together with other people online who might turn on them at any moment. If you've read the "Hunger Games" trilogy, you get the idea.

Gone from "DayZ" are the military factions, battlefields, and tactics that defined "ARMA 2." Instead, players fend for themselves in a massive, open multiplayer world – a world infested with zombies, and, worse still: other actual humans. To get a sense of how seriously people take this game: this image is by Joss Widdowson, the self-styled photojournalist of the "DayZ" world. Joss Widdowson

"DayZ" didn't just transform the playing experience of "ARMA 2" players. "DayZ" snagged thousands of players who had never played "ARMA 2," players who ran out to purchase that niche title in order to run the mod. The result was a sales surge more than quintupling sales for the obscure game's developers.

The "DayZ" mod is so popular that it's becoming its own game, getting a stand-alone release in the near future.

Most modders don't go that far, nor are they caught up in the absurdities of dressing up dragons as WWE world heavyweight champions. The typical modder is a happy warrior for fun in gaming, building new levels, items and abilities that make the experience fun for everyone. And no video game multiverse demonstrates the power of this kind of modding more than "Minecraft."

If you haven't heard, "Minecraft" is an addictive, virtual building game with millions of fans and endless possibilities for creation. Here's a good example of what players have built, block-by-block, in the basic game:

A beautifully appointed city created in "Minecraft." Sanakan_Soryu

As with LEGO, the possibilities of "Minecraft" are functionally infinite – limited only by the scope of your imagination, obsession, and the processing power of your computer. Mods elevate the potential of "Minecraft" ad infinitum. The floating worlds concept below, for instance:

And while some modders just want to build beautiful things like in the clip above, others take the approach that no game – not even a building game – is complete without the possibility of death at the hands of horrific creatures at any moment:

"Minecraft" modded with terrifying enemies. Mojang/YouTube

And others just want the game to better resemble the real world...no matter how bizarre and specific that want might get.

Mojang See that image to the right? A modder, "sick" about the bland way creatures produce offspring in the "Minecraft" world, decided to change all that. Here's an explanation from the mod's page on a community site:

Ever get sick of creepily watching two genderless, identical, ugly squidward-esque villagers breed and instantly pop out offspring? Unrealistic, huh? Well, get sick no more! With Neuro's amazing Realistic Breeding Mod, you can submerse yourself in the beauty of animal reproduction. This mod offers male and female types of many creatures, pregnancy, mating season, and so much more.

All this attention to detail – whether its gorgeous, terrifying or just strange – shows how important modding is to the way many fans play their video games. To give just one more great example of what mods can do, check out how the mod "angry planes" ratchets up the mayhem of the "Grand Theft Auto" universe to a whole new level:

Beware that the "Angry Planes" mod of "Grand Theft Auto V" contains software that could harm your computer! Rockstar Games

Modding, like anything that involves downloading software from the internet, takes some due diligence. If after reading this post you want to experience mods for yourself, try out some of these sites: