I have now bought Assassins Creed 2 for the computer and wanted to play it with an Xbox controller (with cable). When I connect the controller it starts normally but I can't do anything in the game (it works perfectly with other games). What can I do?
Buy the adapter you need.
Do you need an adapter to play AC 2 with controller? That seems a bit suspect to me but ok. Then I have to find the adapter.
You generally need an adapter for all games, at least that was the case with me (so not one for each one, but just one that works for all games).
I have already put the link in my answer
I can play all other games perfectly without an adapter, just not that. I only used a cable most of the time because the cable is faster.
Then unfortunately I can't help you. As I said, it was like this for me
Select the controller in the settings under Control.