What is the Sikh version of creation?

They don't have one. Or, at least, nothing was ever mentioned by the Sikh gurus. They took their task to be teaching people how to live righteous lives, and didn't deem a creation account important in this regard. Similarly, there is no doomsday account either; again, because they didn't believe these to be questions of spirituality: where you came from and where you will go does not affect what you do now, or the person you are.

Note, however, that there are one or two references to Hindu beliefs about the "ages" and other such stuff in the Sikh holy book (these bits were written by Hindus, obviously, and are linked to Hindu beliefs about the creation of mankind). Remember, though, that the Sikh holy book is intended as a guide on how to live ones live (and has poems by both Hindus and Muslims): what's important is the meaning of the Words and not the context used in the poetry. For example, page 145 of the Sikh holy book (the "Sri Guru Granth Sahib"):

The Dark Age of Kali Yuga is the knife, and the kings are butchers; righteousness has sprouted wings and flown away.

In this dark night of falsehood, the moon of Truth is not visible anywhere.

I have searched in vain, and I am so confused;

in this darkness, I cannot find the path.

In egotism, they cry out in pain.

Says Nanak, how will they be saved?

In this Dark Age of Kali Yuga, the Kirtan [singing] of the Lord's Praise has appeared as a Light in the world.

How rare are those few Gurmukhs [good person; literally, "Guru's mouth": one who follows the guru's teachings on how be a good person, as opposed to one who follows the desires of life (greed, egotism etc.)] who swim across to the other side!

The Lord bestows His Glance of Grace;

O Nanak, the Gurmukh receives the jewel.

This should be interpreted as a lament on the evil that people do, and how special it is to find someone who lives by what is right; not a literal endorsement of the belief in "Kali Yuga" and other concepts of creation and ancient eras.