thanks for the feedback.
Looking at X2Go, I see two problems which prevents us from integrating the protocol into Royal TS:
1. The license seems to be GPL, which would mean that when we implement it directly into our product we also must open source our product. I can see that they offer other licenses upon request, so maybe there's a solution for this one.
2. The much bigger problem is the lack of a .NET SDK - at least I wasn't able to find one.
There may be a solution after all:
Royal TS for Windows allows you to include external applications as well:
Maybe you can just create external application connections for your X2Go connections.