I'm trying to debug my mod with dnspy, if everything going well, I will be able to debug line-by-line.
I need to know which version of unity the rimworld is using, so I can using correct version of mono.dll provided by dnspy.
idunno off-hand, but it's logged in the output_log.txt file.
5.6 something something from memory
Maybe you could ask Tynan Sylvester in Twitter or in a Private Message or by emailing him, on what Unity Version that he is using for his game... ;)
no need to bother the man when it's written to the output_log.txt :V