IMO there is no reason why AC4 is not selling better on the Wii U or Rayman, NFS and several more- Look at The Wonderful 101- great game, sold terribly, no excuses other than Nintendo did not market it which is a crime as it was a new IP and cold have used some marketing muscle-
I hate so say it as I own a Wii U (only a wii u, Wii and 3ds) and I want the option to purchase 3rd party games (I have bought several so far) but I think the Wii u will rarely sell respectable # s of anyone s software other than Nintendo's- It seems most people have bought the Wii U purely for Nintendo games and/or as a 2ndary console
The only 2 Wii U games to sell over 1 million (retail) are Nintendo Land (most of which came w the Deluxe) and Mario WiiU which was one of the few decent games available at launch thru Spring 2013-
There are only 2 or 3 games on the Wii U to date that have sold 500k or more (not including the 2 mentioned above)
considering the major software droughts we have had over the 1st year, one would think any decent game that has been available to purchase would have sold reasonably well as choices were so limited- but that was not the case at all- As bad as the hardware numbers have been, It seems like software sales are going to end up even worse- IMO even as the Wi U user base grows, 3rd parties are going to continue to be very wary.