EDIT: It's best to go into this game blind! Only read my post/watch the preview video if you are on the fence or something!
NOTE: If my post about this is TL;DR, just watch the video below. It explains what I just typed in a short one minute and fifteen second video!
I'm sure a good chunk of you have heard or even played this game right now. I'm going to be vague because I don't want to spoil anything. Even the creator of the game, Toby Fox, recommends that if you are interested and go to watch a Let's Play or whatever, just watch a few minutes and then decide if you want to try it yourself. It is a game that really does reach its full potential if you go into it as blind as possible.
The game is an RPG that has a very EarthBound vibe to it. It's certainly not the first game to do so, but it also take RPG tropes and turns them on their head. It's a moderately lengthy game (6-10 hours depending on how you play), but it is worth it to fully explore the game.
Again, this is hardly original for an indie game these days, but the graphics look like a cross between a SNES game and an early DOS game. Oh, and the music is absolutely phenomenal. One of the best RPG soundtracks in ages. Just like something like Shovel Knight, the look works, and adds to the game rather than simply using that kind of style to get nostalgia points.
The combat system is really cool. Instead of simply selecting commands you control a heart (that looks like a Zelda life heart) in a box as you dodge/interact with bullet hell attacks (but not super crazy bullet hell most of time).
There are two main ways to play the game. Though a lot have people have revealed this already, I'll still spoiler tag it. I mean, I'll probably save you some time if you look, but anyway...Plus, I think the creator of the game is cool with people knowing this fact going in, but again, I'll spoiler tag it anyway(SPOILER) Alright, so basically you can either play the game like a typical RPG and fight everything...but you can also literally go through the game without killing anything but selecting the proper commands.
It's just a really good game. The emotional impact it had on me really crept up on me. I want to gush about it some more, but again, I want to be vague for anyone who will end up playing it or even if any of you are in the middle of playing it now.
It is available on Steam or you can straight up buy it from the site itself. It's 10 bucks!
http://undertale.com/
Here is a preview video that is on the site for those lazy to click it!