We are working hard to add support for older GPUs that dont support GL 3.0. Hopefully we can get it in before the release or shortly after.
Also, there seems to be an issue with older CPUs that we are looking into. Add me as a friend to work with us to fix this if possible.
Also, there's lots of requests for SURVIVAL CO-OP. Let us know how interested you are in this. We can plan it out to go in shortly after release.
The first version will be like PvP squads where you and a friend each control 2 soldiers to complete the objectives. How does that sound?