I'll revive this place, and I'll poke a slightly uncomfortable subject to some.
I'll be relating it to a series I've been getting back to pretty fast these last few weeks: Touhou.
Undertale. What it has to do with it.
Some Touhou fans really do not appreciate the many ways Undertale nods back at this series. Undertale pays homage in more ways than one towards Touhou, with supposedly the way you avoid enemy attacks by dodging a soul around being based off of how that series of shooters does a similar thing, quite a few of the "bullet patterns" take inspiration from that series, and there's a theme (that I currently forgot the name of) that even uses instruments with the same soundfont most Touhou musics use.
Even though Undertale is personally really not my thing, I don't really have a problem with this. I think it's nice to know that the creator of the game was a fan of Touhou and wanted to pay homage to it in his game. Many Touhou fans are passionate about their series, so I know very well they would've done similar things to reference it if they were making their own game.
However, I won't actually deny why I know some people have been a bit hostile to those references. I think it sadly has to do with the negative reputation that Undertale and its fans have ended up getting between the Mother/Earthbound community, another series UT draws heavy inspiration from. I think the people that are hostile towards the Touhou references in Undertale, in some ways, basically are scared of having to go through a similar situation the other community went through, where the influx of a few bad apples from the UT community made fans of Mother quite upset that their series ended up attracting those kinds of people because of a fangame.
No, that was not a "Bad Apple" joke. Please. Just because I used the words "Bad" and "Apple" together while talking about Touhou that doesn't mean I'm talking about the famous tune.