“I thought I could ship at least 700 units to stay in business”
I believe it is a business problem. A developer with not much knowledge of Go To Market thing. I would suggest you get a freelance Growth Hacker in revenue sharing or equity basis. Focus on target audience, do some digital marketing(which would cost zero like extensive blogging, super SEO, social media, go to gaming community and promote it), ask people in your network to buy it, etc. Try this and work on the feedback which you are already doing it. Am sure you will get to that 700 units to stay in business. Thanks.