Just a pre-requisite of having no luck?
If so, then games such as these are - by definition -strategic: https://www.warlight.net/MultiPlayer?GameID=9607598
I find this rather hard to believe. Therefore, I wonder - are there more specific guidelines other than the ones mentioned above? If so, what? Assuming a game has these constraints of (supposedly) no luck, when does it no longer become a game of skill?