There's a curious dance that people do when talking about Starseed Pilgrim. They're so afraid of spoiling its magic that they weave in and out trying to avoid saying anything at all, until finally resorting to pointing out that hey - someone you might have heard of liked it, and it's mysterious, so um try it out maybe! I think this undersells the game by making it seem more fragile than it is. If I told you exactly what the relationship between the light world and the dark world is then maybe it would deprive you of one small moment of discovery, but much more of the game is in making use of that relationship, manipulating it once you understand it. I could show you the map I drew of where the various locations are and how they're connected, but it wouldn't even be very useful to you - your world will grow differently to mine. I could tell you every little rule and interaction I've discovered, and it might help you along some, speed up the process for you, but it wouldn't break the game - for there's a difference between facts you've been told and knowledge you understand through experience.
Yes there is exploration and discovery, but the things that are explicitly hidden are not so hard to find. You enter a geometric space that you can move through - you're not told that there are things to find in it, but if you just go ahead and move then you'll start to find them. In this perhaps it demands some personal initiative which is not present in many modern games, but no difficult insights. Simply being unafraid to act without instruction is sufficient. You see a key, you see a lock - there's no tutorial guide telling you to try putting the two together, but do you really need one? And then you see a door with three locks - well I'm not going to spell it out. There are some arbitrary "videogame-y" interactions that you can only really discover by experimenting and observing - stars point to keys, except when they point to locks; hearts become seeds, except when they don't until later - but they aren't really very hard.
This is not to say there are no difficult discoveries, but these are of a very different kind. Starseed Pilgrim's true secrets are the ones hidden in plain view. Basic rules about how plants grow and interact which are discovered in the first few minutes of play end up taking on surprising significance. You have all the tools you need to progress right from the start, but you will need to master them. When you uncover a challenge and realise what you must do to progress, it's easy to go into denial. The lonely pilgrim despairs at their seemingly insurmountable task. There must be something I haven't found yet that will make this easier. There must be a power-up - wall-climbing, double-jump - that will help me here. And so you go searching for secrets where there aren't any, hoping for a way out, trying to avoid doing what you know you must. But there are no short-cuts. You just need to get better at the game.
And that's the secret of Starseed Pilgrim: you can get better at it. It's not about uncovering obtuse facts; it's about mastering a deep system, creatively using its quirks to your advantage, getting better at it until you're able to overcome anything that's thrown at you. Red seeds bloom into a flower if they fall into darkness - initially this seems like a disadvantage because it can crush valuable hearts and enable the darkness to spread more quickly, but eventually you find yourself using it to deliberately to queue up interactions for later. Yellow branches are forced to grow upwards if they can't extend left or right - at first this is usually an accidental waste, but later you will ride them up on purpose. Dripping slime mires you, making movement more difficult, but even this you will find constructive uses for in time - the first time you're pleased to see it rather than disappointed is a beautiful moment. But even if you were told all the rules straight out - which seed best defends against blight, how each world works slightly differently to the others - there would still be much value for you in learning to use them.
So I hope I've managed to dance this dance adequately. I've held back from telling everything I know, but perhaps I've let slip enough to illustrate what the game is like, and to demonstrate that it wouldn't hurt you to be told everything. The pilgrim's magic is strong.