setting up a generic controller in steam doesn't work with the GPWiz - just tested it with steel assault, the GP wiz still isn't being recognized as either a controller or a keyboard.
Setting up a controller in Steam is not super intuitive and it takes some effort to figure it out. It's definitely not a plug and play endeavor. Essentially, you have to enable support for whichever controller you expect to use, in this case a "generic controller". Once enabled, it needs to be selected and then mapped to the functions of an XBOX style controller and then either enabled globally or with different profiles on a per game basis. When I plugged in the GP-Wiz, it was listed as such, as an option to select. After the inputs were mapped, Steam viewed it as an XBOX controller. Once I enabled it for the game, I could then use it to control Street Fighter 5, which was the game I selected for testing.
It's a very powerful system, but with power comes complexity. You will also be trying to configure it to output keys for your specific game of interest, so that is another layer of configuration. As it is not something I use often, I suggest seeking help from those more knowledgeable than I am on the topic of Steam controller configuration. But I can say that Steam definitely sees and can use the GP-Wiz and then send input to games based on your mappings because I just saw it happen
.