dont bother and dont expect a good answer. Ubisoft dont care if a couple of customer are left behind. They do what they want and you read about it on game sites, but some service is to much to ask. Typical French people! I have decided to get my money back from Valve and will pirate this game for the single player. Will buy CODAW for some online fun, cuz activision doenst mind being on steam
Ubisoft has seemingly gone dark with any information about this. My guess? They're debating with Valve behind the scenes regarding deals, or percentage rates. Valve takes 30% of sales, and a money hungry publisher like Ubisoft probably doesn't like that, even if Steam is the best place for it. I wager that's why EA packed it's stuff and left as well.
Ubisofts only official comment on the matter is:
This was when this was only a problem in the UK, but Ubisoft has since yanked these games from Steam worldwide.“We’ve been in discussions with Valve about Assassin’s Creed Unity but for the time being the game is not available via Steam in the UK,” Ubisoft told PCGamesN.
“In the meantime, UK customers wishing to purchase the game digitally can do so by visiting the Uplay store, our retail partners or other digital distributors.”
What are you doing, Ubi?