A kid getting sucked into a video game is cliche. A blob that eats things to get powers is trying too hard to be Kirby without being Kirby. More importantly, why are we making this character transform if our goal is to make a game about nostalgia?
[relevant digression]Have any of you guys played Majora's Mask? Link solves puzzles using masks. Some masks transform his physical body entirely, some give him special powers/abilities, and some influence social situations. Link hides his true face behind masks to accomplish tasks that would otherwise be impossible.
This game mechanic has a point, though. It reveals itself when you visit the moon and talk to the masked children there. They ask Link:
Your true face...
What kind of...face is it?
I wonder...
The face under the mask...
Is that...your true face?
When we're exposed to different situations, we have to be versatile and react appropriately in order to survive. We tend to act differently around different people because we know they have expectations of us, and we strive to meet them so we can benefit. "Be yourself" is good-intentioned advice, but is not necessarily the best advice, and that's what this game is about at its core.
[/relevant digression]
Kirby 64 is a classic, and the sense of discovery you get from that game is fulfilling. Combining power-ups begins to turn into a science, and when you find a good combination you breeze through the level feeling like a God. It doesn't directly communicate any meaningful anecdote to the player, but it doesn't have to because the game is just so interesting.
There's nothing wrong with making a game that's just interesting.
But Paul, you want to create a game that's reminiscent of your past. You don't want this game to be a clone of popular games from your childhood, you want to communicate a message about how playing games used to make you feel.
Unfortunately, I don't know how to turn that thought into a video game right now, but I am thinking about it. I just think that as we're brainstorming here, we should keep these ideas in mind.