Nintendo originally planned Dobutsu no Mori for Nintendo 64DD, a Japan-exclusive hardware expansion drive outfitted with extra memory and an internal clock. When the add-on proved to be a bust, Nintendo pivoted, releasing the game for Nintendo 64 instead. The company built an internal clock into the cartridge, enabling the game's most important mechanic and biggest selling point: It ran in real-time, cycling through day and night in tune with the real world. But that feature wasn't fully realized until Dobutsu no Mori +, a.k.a. Animal Crossing, on GameCube. That console's clock allowed the game to keep going even while you weren't playing. Neighbors would remember how long it had been since you last logged in — and immediately make you feel guilty for not visiting them in more than a month. Plus, your town would suddenly be littered with weeds. That clock might keep the game running even when you weren't playing.

The biggest draw to Animal Crossing is in the name itself: Your randomly generated village is populated with friendly anthropomorphic mammals. Starting a new town was so exciting because it meant a whole new set of neighbors to befriend — and quickly start running errands for. That part wasn't so great, especially because the raccoon loan shark Tom Nook was running you ragged. But each animal villager had a distinct personality, with a quirky catchphrase, a set of likes and dislikes, and a particular fashion sense. Meeting all of them required starting a whole bunch of new towns and visiting as many of your friends' places as possible, and that kind of social play was pretty innovative for Nintendo.

Traveling around in the GameCube version of Animal Crossing was as quick as sticking a second memory card in the console. Your villager would hop on a train and step off onto the platform of another town, filled with its own unique items, inhabitants and local fruit. Certain things in Animal Crossing always remained the same: Tom Nook was there to rip you off, and Mayor Tortimer was sleeping on the job. But visiting other people's towns — or your own, if you bought several memory cards to create new ones — always offered something new to see.

For a seemingly slow-paced game — the only real objective is to pay off your loans to release yourself from Tom Nook's financial clutches — Animal Crossing sure had a lot of things to do. Namely, the game set aside a lot of time for partying. Since Animal Crossing subscribed to our calendar, the animal villagers celebrated the same holidays we did. There was Halloween, where you'd get candy from a sentient jack-o-lantern; Christmas, when a reindeer would gift you toys; and even the Fourth of July, in the American version of the game. More frequently were the bug catching contests and fishing tourneys, plus surprise visits from strangers who brought their own challenges. The one downside of these was that it was hard to convince your real family that you had to ditch the annual family New Year's Eve countdown because the fireworks at midnight in your Animal Crossing town were way cooler.

One of the coolest Nintendo Easter eggs is "Totaka's Song," a little jingle that makes an appearance in many of the company's games. Named for composer Kazumi Totaka, the tune is recognizable to fans who have played games as diverse as Mario Paint, Luigi's Mansion and Wii Sports. Totaka worked on Animal Crossing, too, and instead of just sticking his 19-note melody somewhere into the soundtrack, the development team created a character in his name: Totakeke "K.K." Slider, the swoon-worthy canine bard. Every Saturday night — or, heck, whenever you wanted, if you dared to "time travel" — K.K. sat by the steps of the train station, guitar in hand, ready to perform a song for you on the fly. Thus was born one of gaming's most creative and memorable vocalists. He might not have been much of a lyricist, but boy could he sing those notes with the best of them.

Maybe it's weird to cite this as Animal Crossing's best feature, but it's pretty undeniably cool that you could play NES games while seated in your virtual living room. Picking up the games was a bit of a crapshoot: You either had to get lucky playing the lottery or enter promotional codes. But the library was expansive, featuring games like Tennis, Balloon Fight and Donkey Kong. You could even unlock Super Mario Bros. and The Legend of Zelda, if you knew the right codes. Animal Crossing basically had the most unbeatable minigame collection ever — except these were fully featured versions of the classics, not just demos. Nintendo's Virtual Console on later consoles meant that this feature began and ended with the series' first installment.