I think it goes without saying that this post will have crazy spoilers for all routes of the game. Only if you are done with the game and ready to embrace all spoilers should you read any further, not that I recommend reading further anyway because you're probably gonna disagree and get angry, but you're still reading so I'm screwed anyway. Welp!
So Undertale happened. A game that has taken the Internet by storm for its take on morality in games, music and overall good story and characters. I agree with many that it's a very good game and one that will be remembered for quite some time, comparable with (if not surpassing) many big name games. I've finished the true pacifist [sic] route twice, with a full reset in the middle, the second play through trying other options and seeing more things I may have missed the first time round. On my other computer, I've been playing the genocide [sic] route to get a bit more context for a few things and out of pure curiosity. After playing the game so much, I could write a lot about what I really like about the game, but that would just be repeating what the rest of the Internet is saying. Instead, I think I will talk about the bits I didn't like, or at least came away from it with a sour taste in my mouth.
First off, there were a few parts of the game where it seems unnecessarily obtuse in imparting information that you need in order to do something, or making it clear that something was even possible in the first place. The most notable example of this was the battle with Toriel. I wonder how many people were convinced that they had no other choice but to kill them to continue? I sure was. I killed them on my first run through. I also personally know of at least one other person who is convinced that there is a way, but they can't find it. I get the message though. "Determination" and all that shit. "You must be determined to hammer an option in the game that isn't the first thing you select in almost any other encounter in order to spare this person". Toriel's name isn't yellow/pink, so the game has taught you that this monster can't be spared yet, so do something else. Maybe to other people it's super obvious and I just need to "get good". Either way, it felt like an oversight in a game where everything is super intentional and, thus, out of place. Honestly, if Toriel's and Asgore's fights were reversed, where Toriel would destroy the "mercy" button until you got their health low, while Asgore kept the "mercy" option, but did what Toriel did, it would be way more obvious because the "mercy" button remained intact, and you would have to survive the attacks until you hit the button enough times. I'm not sure if people would agree with that one (probably not) but that's one thing I didn't like much.
Okay, next up is the ending to the neutral [sic] run, or rather the bit with Flowey. Flowey gives you a hint on how to get the "true" pacifist ending if you spare them. If you don't spare them, you don't get the hint and, thus, no clue on how to progress to the true pacifist, or even that there was one in the first place. Obviously, the Internet exists, but "after leaving the core, backtrack until you get a phone call from Undyne" seems, much like sparing Toriel, completely non-obvious unless you get that hint. I can only assume that someone going through the entire game again, but this time being as pacifist as possible, getting the Flowey message and then going to find Alphys is what is expected, and probably what I would've done if the Internet didn't exist and I found out about it through osmosis.
The big thing that negatively affects the game for me was the ending to true pacifist [sic]. Once you've beat neutral once and probably gone through the entire game again because you killed Toriel and then finished with the Asriel fights, you then find out that the name you typed in at the start was not the name of the character you were playing. Once you trawl through all the game's text and piece it together, it turns out you were actually naming the first human who fell down a long time ago and was adopted by Toriel and Asgore. The character you were playing as is actually called "Frisk".
Now bear with me a second here while I get psychological on you.
Imagine you are playing through a role playing game. You name the character you're playing as after yourself. You style them after yourself. You play as them. That character is you. Then imagine that, in the game, you got killed and replaced by someone else with a different name, only they look like your character did.
They are the ones everyone is happy to see.
They are the ones attributed to saving the world.
They took the happiness that should've been mine.
In Undertale, just as you think you've saved the world, it takes that glory away from you and gives it to "Frisk" instead.
I felt cheated out of my happy ending.
I was no longer a part of this story.
I became a simple bystander as "Frisk" was praised by everyone.
Is this the actual motivation behind doing a genocide run? Putting that ending aside, there's no real motivation behind doing a genocide run because all the characters are lovely. You wouldn't want to harm them after a true pacifist run. But then the Frisk thing happens and I'm left thinking "but I did this. I helped everyone. Frisk isn't me." In the genocide run, everyone refers to you by the name you put in. It's definitely you who is the cold blooded murderer, not Frisk. So the game has you remembered as being a murderer, or someone else entirely. To actually leave your mark in the game world, kill everything.
To try and shoehorn yourself back in, you can assume that the physical human that you are moving about the underworld is called Frisk, but you are possessing the human as a spirit or "soul" as the first fallen human to either make up for what you did when you first fell down or to finish what you started and kill everything. It's not exactly ideal though, as you can't claim credit for something when you're a ghost.
Honestly, the first two things are minor niggles that were a little frustrating at the time, but it's not that big a deal. The final one though is why, despite massively enjoying Undertale, it left me with a sour taste in my mouth. Regardless of that though, I'll certainly be interested in whatever Toby Fox does next.