In a neutral playthtough, likely a first-run where a player is likely to have killed a few monsters, Flowey makes some calls on what kind of "true end" you're going for and gives you pointers to achieve that end. (this is an assumption based on my own experience.) It's safe to say he's playing around with you, letting you be challenged, in turn giving him something to look forward to. He's been there for a long time, and you're the most interesting thing to happen in a long time.
In a pacifist playthrough, he doesn't want you to win, because not only will everyone else leave, but there won't be much else for you, the player to do either. You'll leave and maybe never come back. This is a very meta motivation for a villain, but anyone who's both killed and spared Toriel knows that's part of what he is.
In a no mercy play, though, he has second thoughts about assisting you, because you are ending all encounters with death. You are done with the game when everyone else is done being an obstacle. This is where Chara calls you out on the desire for GAINS *flex* like most other RPGS work to let you crush foes. In this scenario, there is little anyone, let alone Flowey/Asriel, can do to keep you invested in the game, since by the time you see him again you've already bested the "secret" boss, Sans.
tl;dr, Asriel is the manifestation of the game wanting you to keep playing the game. I would have said he's the game creator's self-insertion, but I think he's already confirmed that he's the dog that shows up randomly to fuck with you and the other characters.
Had a dream where i was a low rank member of a team equipped to fight off a mysterious invasion of radioactive beings from who-knows. I somehow developed the ability to see the radiation they emitted (like a heat map) and the encounters were.like a tactical rpg (with a game over and retry). I lead the team to a fortress giving off loads of the radiation, but when we get inside, the radiation disappears from my vision. We go outside to find our exit path is in flames, and the other members of our team are irradiated and trying to stop us. The dream ends as I am trying to learn what the invaders' true motivations are by talking to the "infected."
I want to design a game that takes the player through the life of a girl with an extraordinary power that sets her apart from the people she meets...
in early life she set herself apart by not knowing she could see something others could not, but was sheltered by community leaders that understood the validity of her observations despite lack of visible evidence. Once those leaders are made unavailable, or she leaves the community, she discovers her insights are neither common nor widely appreciated and could be completely misinterpreted if not used carefully. The player must then choose how they wish to interact with numerous people using these insights to achieve her goals, one step at a time.
her journey starts in her home town, on the edges of a great forest filled with natural wonders and hazards. Scouts uncover an increase in hostile mutations, and her mother is brutally assaulted. When she finds her mother, alive but weak and delirious, her second sight is inadvertently drawn in to her mother's consciousness, affected by foreign energies, and pulls her out of her stupor. For this display of extraordinary ability, she is granted a selection of opportunities for her future outside of the town.
Each of those choices are presented to the player as offering different styles of game-play and additional playable characters. At this point in the game, there are already several different possible outcomes based on the player's choices. Have they killed anything? Did they help any of the villagers? How helpful were they? Did they stand still while talking to people, or did they pick up everything that wasn't nailed down? It should be made clear that the main character is the player's avatar in a realm of people with unique perspectives, and their choices will affect those perspectives (despite being 100% programmed.)
A truly advanced game would involve some kind of AI that could form its own opinions and reactions, but I don't foresee that as being possible (or playable) any time soon. I believe responses to player actions should be predictable to players with enough experience interpreting the reactions of other people. As such, the most important development point of this game would be the NPCs' expression of emotion to the events in the game. These things are typically developed first by writers, and then by visual artists and voice actors with the assistance of a director.
This is not to say that the game-play is any less important, but if the objective is to achieve an outcome through character interaction, the rest of the game-play should simply be a chance for the player to reflect upon the interactions they've already had. I would not force these reflections upon the player; having what is supposed to be the main character's thoughts read to me 5 minutes after I've thought of them myself is not what I call entertainment. If a player is unable to reflect on the events that have transpired and draw reasonable conclusions in advance, they should be given the opportunity to be surprised and act accordingly, without being outright punished.
But then, how will the game differentiate between a player that is surprised by an event and one that saw it a mile away? Will it even be necessary?