Just so we're clear, you want to require the person to choose 1 or 2 colors, before they can purchase the product? I think requiring it before they add it to the cart is a better idea.

I think the optimal solution, Überdudes, is to make an option for Requiring an attribute. As it stands now the first option in the drop-down list is the one automatically selected. It'd be better if it read "Choose a [option]" and if one is not selected, kick them back to the form.

To do this, Sue, might require a custom module and the use of hook_form_alter.

EDIT: Hey uberdudes, after working on this, I realized a couple features I'd like to see in the next beta For Sue's needs at least, her situation would be made easier if she could make an option required, and also, if an attribute could be a multiple select list.

Then we'd have to use hook_form_alter to check and see how many values were selected in the list, and if it wasn't at least 2 (in her case) throw an error and kick back to the add_to_product form. (But the flexibility to choose a combination and require a certain number of options seems an interesting thing to add).

If you think that's doable I can add it to the feature request queue (There is one, right? Hehe.)

We also need this functionality and have been looking into making a module for it. What we require is the default option to read "Please select..." and for that option to prompt the user to select a proper option. I think the ideal solution would be a checkbox next to each option saying something like "default option" or "don't allow checkout". If anyone has better ideas I'd love to hear them. Also, an outline of how to do this in a module would be great before embarking on it and likely getting it wrong!

This has been fixed in core.