You can't lose. Actually, most of the challenge and complexity that earlier levels build up to is gone. There's only enemies lined up to make simple pairs, allowing the player to go faster and faster as the background and the music go wild.
Slowly, the game takes control away from the player until eventually, you're not playing at all—it's just a visual medley. Like a music visualizer, if you will. Then, the game starts over.
The final level is called "Eye of the Duck." What an odd name for a level, I thought! I wondered if there was something awe-inducing about duck eyes that I was missing, so I looked up, well...duck eyes. And sure! Duck eyes are pretty okay.
Actually, though, 'eye of the duck' is a reference to David Lynch and his ideas regarding perfect scenes in movies which truly capture the essence of a work. In a painting of a duck, there's lots of different textures, but the real 'jewel' of the work is the eye. And the eye has to be in exactly the right place, else it looks weird, right? The eye can only be where eyes go.
It's kind of, uh, out there as a metaphor—but I suppose that makes it go hand in hand with the equally trippy Dyad, eh?
Anyways, there's a reason why Dyad's ending works so well as an 'eye of the duck.' Much of the enjoyment of the game comes from the ability to vibe with it. If you're not able to just go with the flow, you won't go very far. What better way to let go than to...straight up let go because you can't play anymore?
The best way to ease you into that idea is to make the player stop worrying about too many things, so when the only thing you can do is go faster and there's no way to fail, the final level of Dyad just feels so, so right.
I can't help but wonder if the game couldn't have stood on its own with just a giant level like that, that goes on and on indefinitely.
Either way, Dyad's ending is perfect.