- My biggest issue was the writing and pacing. I thought the humor was mostly awful, and since there's a lot of it, it's a big issue for me. There were a lot of 'jokes' that were just dragged out way too far, far beyond the point of killing said 'joke'. As for writing in general, I came away from it liking approximately 0 characters, so, yea...I don't think that's what they were going for. There were also generally so many interruptions for small bits of dialogue (which as I said, I'm not a fan of already) that a lot of the time didn't even feel like they added anything to the game/character in question. This in itself isn't an issue, but the fact that it halted the gameplay entirely every time one popped up was just frustrating, to have constant text boxes pop up and bring you to a complete halt whilst you're plodding along just to tell you 3 words of dialogue.
- More on the pacing, and some design; as I said, my friends were already excusing a lot of the game as "oh, this bit is boring" with nothing really happening or dialogue going on far longer than it needed to, but even if they weren't there was a significant enough amount of areas that were just horribly paced and designed. There were so many parts of the game where I assumed I was just walking down an endless hallway. I was prepared for that 'endless hallway' puzzle the entire game, because it felt like I was in one so many times that I assumed the dev was really trying to 'throw me off' so I would fall for it when it eventually did happen...That 'endless hallway' puzzle never happened though...It was just bad design.
- Meme humor...So much meme humor...Damn, so much of that humor is going to age badly.
- I also don't see the big deal with the 'kill or spare' stuff as a gameplay mechanic (I gathered that it has a bigger effect on story than gameplay, but I've already established I thought the writing was w*nk anyway). 'Killing' and 'not killing' overall didn't feel like unique things to me from a gameplay perspective, minus the obvious changes you'll get with dialogue and endings. Again, since this is the 'big selling point', it was a 'big issue' to me. Mechanically, there wasn't all that much separating them. It was like comparing green apples with red apples. When something 'mechanically' changes something about the game, I want it to be as drastic a change in gameplay as choosing between 'Rambo mode' and '0 alerts/0 kills' in MGS, or 'shoving all your skill points in melee' and 'all in charisma' in an RPG (which also makes a good amount of RPG's 'pacifist' with 'multiple endings'...Can we stop using that as the sole selling point for Undertale as though it created the concept?)