1. A deep RPG story made by indie developer Toby Fox.
2. The place where retarded FNaF fanboys come to flock now, since FNaF is dead.
3. Sans the skeleton.
Person 1: Hey have you played Undertale yet? It's a pretty kick-ass game!
Person 2: Fine, only because of that spooky skeleton you fight at one of the endings.
FNaF Fan: OMG UR PLAYING UNDERTALE!!! IT SUXXX! BUT IM ONLY HERE BECUZ FNAF IS DEEEEED!!!!one
by A Potato-loving Cactus February 19, 2016
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A low quality game with very little story, generic characters, and zero replay value. It tries to break the fourth wall with the "characters know they're in a game" cliché. It's just a bunch of clichés together into a walking simulator. All you do is walk and meet people. When you meet people, all you do is hit the same buttons over and over until they leave. Then you walk again. Then you repeat the process with no character development or story. It usually would take about a week of non-stop gaming to play through the whole thing. You pay to spend at least a week of your life virtually walking then hitting the same buttons with characters that obviously had no effort put into them. It is considered the best thing to ever hit humanity.
(How the fans act)
Fan 1: Undertale is so great! I played through the whole thing twelve times this summer!
Fan 2: If Undertale isn't your whole life, you should die because you're a pathetic loser who no-one cares about.
Fan 3: *Talks about Undertale constantly at school, texts friends about the game ending that they just got that they had gotten three times in the past month and told you about every time, and invites friends over to watch them play Undertale*
Fan 4: Undertale is better than any other game and if you think otherwise you're an idiot who isn't worthy of talking to me.
by AJ45 June 28, 2016
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undertale, is when you send a message on a groupchat, but the internet doesnt let the message send while you are still able to the see other group memembers interact
¨dude did you saw the new chapter of kaiji
¨yeah¨

*uhm guys, my messages arent sending, oh my god, im trapped in undertale, somene help me, GUYS STOP TALKING I MY MESSAGES WONT SEND*
by kemafili May 26, 2019
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Cancer game meant for morons and idiots
Wow! Look at all the undertale being played right now!
by Starvingcannibal December 16, 2015
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A condition caused by the height and weight ratio not working out just right.
She's not overweight, she's undertall.
by cowboy_up September 4, 2009
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I'm an undertaler, too.
by Dogaahs April 17, 2016
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