At first I didn't think this was possible - and since the client rejected a touch screen interface, I have been researching multiple joysticks.

My problem with commercially available joysticks is they are overburdoned with buttons, unless we invest the time and money in custom building 80's arcade style joysticks. But either way this added a tremendous overhead to our project.

This .net library seems to hold some of the answers. It's ok that we are restricted to XP, because being a museum exhibition, we have control over the client environment. Questions for me still remain about how the kids will interact with the space. A mouse needs a flat smooth surface, and there's not much space for desks. Also, any learners be comfortable with a mouse?

The motivation for simultaneous mouse inputs is the fear that older or tech savvy kids will dominate, leaving little agency to the others in the group. Research I found here seems to back this up.

I've downloaded Microsoft's Visual C# Express edition and have been playing around wrapping the Flash game in a .net app. So far so good - but there's a long way to go.