Doom - one of the most influential video games ever made - is 20 years old.
ID Software's classic and iconic first-person shooter was first uploaded to a server at the University of Wisconsin late on 9 December, 1993 - and it's fair to say that quite quickly it changed video games forever.
In the game, the player has to hunt through mazes for keys and solve puzzles while battling raging hordes of monsters, demons and zombies.
Looking back, it might not immediately seem that groundbreaking: Doom was not the first video game to use a first-person 'behind the gun' viewpoint, after all, and certainly not the first to use 3D-like graphics, maze hunts or most of its other key mechanics.
But nothing before Doom managed to put those elements together in a way that was so fast, so convincing - and so scary. For it wasn't the action alone, but rather the suspense and genuine fear the game inspired, that changed the industry and won legions of fans.
Other key factors in its success ranged from its 'shareware' revenue model - in which free copies of the first levels were given away to encourage players to buy the full game - to its expandability via level editors and its simple multiplayer "Deathmatch" mode, which went on to influence everything up to the latest Call of Duty and Battlefield games.
Needless to say, Doom was a huge success, recording millions of sales and gaining a release on virtually every games console around, including the Game Boy Advance. Being able to run the game became essentially synonymous with usefulness as a computing device.
To read more about Doom, check out this amazing write-up of the game's history. We also have a review of the old game (as well as Doom 3) here. But perhaps the best way to remember it is to watch some of its best moments:
Pokemon X & Y (Nintendo 3DS)
The latest Pokemon is the best yet, adding totally revamped and (partially) 3D graphics, great new pocket-monsters to collect, handy experience-sharing features and - as ever - hugely addictive quests to build you team and defeat whoever, for whatever reason. <a href="http://www.huffingtonpost.co.uk/2013/10/04/pokemon-x-y-review-3ds_n_4037123.html" target="_blank">We loved it in our review</a>, and for Pokemon fans it's a must.
Forza 5 (Xbox One)
Forza 5 is the Xbox One's flagship release racer, and it looks utterly amazing in person. The graphics and handling really are a step above anything you could have seen on the previous generation, and it gives us hope that there's a lot more graphical and mechanical power to wring from the next-gen in the year's to come.
Killzone: Mercenary (PS Vita)
Sony's handheld games machine hasn't had a lot of stand-out AAA games this year (indies is a different story). But the latest Killzone was different. <a href="http://www.huffingtonpost.co.uk/2013/09/11/killzone-mercenary-review_n_3906328.html" target="_blank">It's a rock-solid, feature complete FPS</a> with a dramatic (if silly) storyline, clever level design and touch-enabled features that make the best of the PS Vita's unique hardware.
Dead Rising 3 (Xbox One)
There are a few key things that the next-gen consoles enable you to do. One of them is mow down literally hundreds - <em>literally</em> hundreds - of zombies at once in a tank attached to a deadly fireworks rocket. It's amazing fun - shallow? Yes. Hilarious? Also yes.
Bioshock Infinite (Multi-Platform)
Bioshock Infinite came out much earlier this year - but Christmas is a perfect time to finally pick it up and give it the time it deserves. With an amazingly engaging storyline and rock-solid combat mechanics, it's hard to find fault with a landmark game of the generation. And with the new DLC - which takes you back to the underwater world of the previous two Bioshock games - there's never been a better reason to play it through again.
The Last Of Us (PS3)
Critically lauded at the time of its release, and rightly so, The Last Of Us is another gold-plated classic of the generation - and Christmas is exactly the right time to go back and see why it made such an impact for yourself.
Super Mario 3D World (Nintendo Wii U)
The new 3D Super Mario game is the best in the long-running plumber's series of Princess (or in this case, fairy) rescuing adventures in years. The 3D worlds themselves are charming, fun, fast and creative. It's a riot in multiplayer, and the new "Cat" power-up is adorable.
Make no mistake - the PS4 has its share of big-budget AAA games at launch. But this family-oriented 3D platform adventure is up there with the best of them thanks to its beautiful next-gen graphics, attractive and welcoming design and innovative use of the PS4's raw power to tell a story - as well as render amazing chainsaws.
Zoo Tycoon (Xbox One)
The idea of Zoo Tycoon might not set your heart racing. But trust us - there's something about building an ethical animal park with nothing but 12 kinds of bear, which you can feed with your own hands thanks to the new Kinect - which is oddly, totally thrilling.
Assassin's Creed IV: Black Flag (Multi-Platform)
The new Assassin's Creed <a href="http://www.huffingtonpost.co.uk/2013/10/30/assassins-creed-4-uk-review_n_4177896.html" target="_blank">is a snappy, fast and engaging open-world title</a> which rejects the last instalment's lumbering story for a truly free, fun and exciting adventure.