Kingcell Solitaire has the same layout and essential gameplay as Free cell.
There are a couple of differences:
Only Kings can be placed on the Tableau.
Suite isn't important for cards placed on the Tableau.
Remember that a Tableau space is wasted if you don't have a King free to place into it. Regarding difficulty that fact the suite isn't important more than makes up for this, and if anything unbalances the game by making it too easy.