Our plan is to release as many of our back catalog books as we can in PDF format. 

Unfortunately, circumstance prevents us from including literally every book. 

The licenses on some books (such as the GURPS Conan line) have long since run out, and we cannot make those into PDFs. 

But we will do our best to ensure our catalog gets uploaded digitally over time. 

If this does not answer your question, please open a new ticket.