Still,

Nick had made a post on 10 things we didnt know about spiral knights. He left the #10 one empty for us to find out. So i went around looking for secrets :/ but apparently someone had already found it out and i hadnt. Congratz to that person... but then, can someone explain the following?

"They say the answer to a question is always present in the question itself"

Quoting Nick:
10. There's lots of secrets in the game, many that we will unveil as we continue to develop the world. However there is one that players see every day that so far as we've seen, no one has ever figured it out. Curious!

There's lots of secrets in the game... Yes we know that, for one, the ghost block in FSC which mysteriously appears when you hit a switch hidden by a box.
They havent unveiled it tho.
So that cant be one of the secret he is refering to. Secrets they have unveiled eh? hmm... its curious as they have unveiled some things which were rather mysteries, rather than secrets.. for example, the open space in the arcade, where the krozmo coin alchemy machine and the fiend manager lies, was open earlier. People wondered what would come there. So in one way, they uncover mysteries which goggle knights. And yes, that is, in a way, developing the world.

Now to the secret, or rather the mystery, he was refering to. He said players see it everyday. Now what is one thing people see everyday? HAVEN, yes. So that means clockworks is out of the question.
Now there are a few i want to enumerate in the order of decreasing possibility. But there is still a chance that the least possible one might be the actual one.
First we start with the townsquare, where EVERYONE spawns.

1) The Down part of Haven. In town square, where everyone spawns, you know there is a path to the south which is blocked. No one really knows whats there beyond that. Since we have landed on this planet, we need to know whats down there.
2) This is with reference to the previous one. The so-called guard guarding this, is actually a trojan, holding a leviathan and a shield.
3) The screens above the auction house and the face of it. The screens seem to be showing a strange dialect, which appears to be chineese or japaneese idk which. Since i dont know either of those languages, i asked some of my friends. They said it was not japaneese or chineese. Or maybe the words were too small... could it be another dialect?
4) The front face of the auction house. There are snipes wearing transparent caps sitting on crowns and some strangers in there. I dont know if this is some kind of secret, but yeah.
5) The only stranger with no snipes on him, other than basil, is Hailoh, the first stranger who meets all the new recruits. He is right where you spawn, before those 2 gates.
6) There is a pod on the haven training hall... idk if this can be called a secret, but arent pods only there in the rescue camp?
7) The chimneys and exhaust fans etc along the bottom look like parts of houses...
8) I found this out actually after i posted this comment. Am adding this in editting. The pipelines, the yellow ones, they all seem to lead to the arcade, but none of them ever appear even once in the arcade.. what is in those things? hmm...
Now we can move on to the bazaar, Not much here tho.

1) The pond always intrigued me... as if it had something about it. It never evaporates.. might it be a wishing well? lol
2) Greave, the armor merchant, is the only stranger with a HUGE backpack.
3) HUUUGE open space in the bottom.
4) Vatel sells 2* recipes and his flag shows a poison vial... idk what it means.
5) Bosco never seems to complete his mecha knight. If my memory serves right, back in beta, or some time after it, the robot was sitting still, not moving. Now its up and working...

And now the arcade, for one thing i thought the secret would be in here for sure, but i didnt find anything relavent.

1) The huge holes behind the krozmo coin area, the mineral deposit explainer, or whatever, area etc.
2) When you stand that the gates, looking down, you can see another lift and some space before it. That is where you spawn :D

Thats about it. I couldnt find anymore. Now idk if #10 has already appeared :P.

Thanks for taking time to read all this, and if you have a suitable explanation, please! i want to hear it. So many unsolved mysteries in my mind o.O