At first glace Undertale looks like a simple throwback to classic top-down role-playing games. Yet, as you make your way through this world the game will challenge every preconceived notion of a traditional rpg. Its a very heavy decision driven narrative with an array of choices in each fight. You can play through the game sparing or cutting down everyone you come across. It is very hard to go into any detail about this journey without spoiling anything since this game chock-full of surprises. If the concept already peeks your interest I'd definitely just recommend picking up the game or simply watch someone play it for the first time on YouTube. Otherwise, as you read on I'll try to be as vague as I can while giving enough detail to hopefully help make a purchasing decision.
Undertale takes place in a world of monsters and humans. The humans drove the monsters underground in a great war. Many years later a human child climbs up a mountain and falls into the world of monsters. As this child you will explore this unfamiliar world filled with many different puzzles and an array of memorable characters. This is a fairly linear experience as far a maps go making it easier for the game to keep the focus on storytelling. Still there are many rooms and story plots that are easy to skip if you are not actively paying attention. The npcs and signs add a lot of charm to the narrative and would be a shame to pass over them over.
When you are not moving around the map much of the game will take place in fights. When you enter combat there is a heart trapped in a small box; this represents your soul. As the fight progresses there will be objects that bounce and fly through the box which if they hit your soul will deal damage to you. You can move around to try on avoid these objects and use items to help reduce and heal points of damage. On your turn there will be a menu consisting of four main options; fight, act, items, and mercy. By fighting you simply attack the monsters health while acting lets you try to settle things without dealing damage. After the monsters feel fulfilled you can select mercy to spare them or flee from danger.
Visually this game looks like it could have been made in RPG maker. The backgrounds are effective but very simple. The black and white sprites for the different monsters are bit more impressive and are generally quite cute. I think part of the reason for the retro, NES inspired, graphics is to help get the player into a certain state of mind. The game wants you to think that your getting into a old-school experience in order to make each twist stand out that much more. Lets not forget the soundtrack. Although a bit like chiptunes the music is wonderfully diverse and catchy. Clearly the sound design is one of the standout elements of Undertale.
If nothing else Undertale is simply different. Players looking for a totally fresh and unique experience have no need to look any farther. On the other hand anyone looking a simple, straight-forward, role-playing games is definitely going to get more than they bargained for with this wild ride. Undertale really is an emotional roller-coaster, both in terms of story and gameplay. Although I did enjoy the story-line and characters quite a bit the reflex based gameplay did start to wear on me towards the end of the game. Undertale can be a bit more taxing than seems really necessary. If you can get past some of the hurdles I believe many players will come the enjoy their stay in this world and fondly remember the characters they have met along the way.