Yeah that is better, thx
This doesn’t work as well in a fantasy universe when answers like “I just cast mirror image” and “flesh golem carefully constructed to look like me” are perfectly valid answers.
My first is a number
My second another
And each, I assure you
Will rhyme with the other
My first I can say
Is one-fifth of my second
And when both are together
A long period reckoned
Four-score, the trick is most people won’t think of trying non-standard numbers like “score” for a while.
The old computer game The Crimson Crown has three delightfully creepy riddles I loved as a kid:
Hands I do not have, yet I grasp so tight.
I love darkness, my enemy is light.
Both the mighty and low know me well,
For in the hearts of men do I dwell!
Fear
I wonder as I wander: where am I?
I shed tears, yet I cannot cry,
I trek, but cannot walk, swim or fly,
I am born to die. Say, what am I?
Cloud
I am, I’m not. I visit young and old,
Some I make timid and some I make bold,
Unwise is the one who pokes fun at me.
Beware, for I am a shadow of thee.
Death
Why did the chicken cross the road?
Because it was too long to go around.
I once came close to stumping the Demon Asmodeus with this, but he Vader-choked the answer out of me.
A friend on mine used this on us when he was DM. We only were able to continue our quest by killing the Minotaur that asked the riddle.
And here I thought cows were the stupid ones.
An eye in a blue face
Saw an eye in a green face.
“This eye is to that eye,”
Said the first eye,
“But on a low, not a high.”
Sunshine on daisies
It took me a while to get it, even after I knew the answer.
Most fantasy fans will know that one, Yooperthing. It’s from The Hobbit.
I was going to go with ‘Temporal Anomoly, one is a time traveler’
Since the matchmaker never asked if they have the same mother, another answer is that they’re half-sisters, with different mothers.
Of course, in these settings the riddle is usually the key to unlocking some other objective, so just because an answer is valid, does not make it correct. The job would be to find the correct answer not just any answer. Having multiple possibilities just makes it that much more maddening for the adventurers.
ETA: just realized this was a zombie after it ate my brain.
In one of the campaigns I ran, I had a shifting maze. It read:
Dire Forrest has a shifting Maze That bears this legend:
Pretend as if you’re playing a game,
the way to get through is just the same
inside the castle
you’ll use the code
and then you’ll hit
the mother lode
the way to get through the maze is
thusly:
Up
Up
Down
Down
Left
Right
Left
Right
Then:
A
B
(Represented by Rhunes in the earth)(
It’s a reference to the konami code. I had a lot of fun with that one 
Dang! didn’t see this was an old thread!
That’s not really a fair riddle, though, because it requires out-of-game knowledge. Sure, some of your players probably know the old Konami code, but there’s no way the characters would.
Well, you’re right in that it’s hardly self-evident, yet somehow somone figured it out in real life. Maybe the secret was leaked, maybe it was discovered by accident/observation. No reason some old dude couldn’t have gone through the dungeon in the past and learned its secrets and now lives nearby. Maybe he’s known as the crazy old geezer down by the creek who claims to have seen King Scrogg’s treasure but was run off by some resident nasty guardians. And nobody really believes a word…
ETA: I mean really, the point of a riddle is to control access to only allow in “those in the know.” I’m not going to rely on “30 white horses on a red hill now thay stamp, now they champ, now they stand still” to be the principle barrier between my horde and some pimp from the shire. It should be nearly impossible to figure out unless you have a critical piece of evidence or a unique perspective.
No. The point of a riddle is that anybody can figure it out if they can get into the thoughtspace of the riddle. That’s the difference between “tell me the Konami Code” / “what’s in my pockets” and “what has four legs at dawn, three at…”
Yep, anyone can get a riddle. A question with dozens of possible answers, only one of which is correct, or a series of directions is a password, not a riddle.
ETA: For an example of a password that sounds like a riddle, think of the Dark Brotherhood questions in the Elder Scrolls. In Oblivion, the sanctuary door asks, “What is the color of night?”. The answer could be Black, Dark Blue, Black with White Dots… Literally anything. But there’s only one answer that gets you in.
I am the end of Before and I am the beginning of the End. What am I?
The letter E
In which case, the DM needs to put that old geezer in the game, and the challenge then becomes, do the players track him down and believe him, not whether they can figure out the riddle themselves.
And even then, it’s not really a riddle. It’s just directions.
Here’s an old one I used,
Brothers and sisters, I have none.
But that man’s father, is my fathers son.
Who is that man.
My son.
Hope you like it.