No, it is not.
Why would it be impossible? How did you play it?
Thank you, I wanted to confirm.
And indeed, it would not be impossible to win the Solo mode under the conditions stated in the rules, such as a perfect score (meaning every cards from a set must be emtombed but with no duplicates). But it would take forever to empty the stock deck and the pyramid and the player deck would be full of cards that should not be emtombed.