Actually Milestone 1.6.1
projectlibre.exe cannot detect 64-bit Java.
Workarounds: Execute jar file directly (or execute bat file) or
Install 32 bit Java alongside 64-bit Java
Java 1.8.0 u45 used.
Since the default icon points to projectlibre.exe this might cause problems for everyday users.
I have never seen NSI before and don't know if you can build a dual 32/64 bit executable in one step. However I did use NSI 3.0B1, and added "SetRegView 64" on line 83 in projectlibre.nsi. This way I get a version of the executable that detects java in Windows 64. It probably don't work in windows 32 bit.
This new excutable I call projectlibre64.exe and it works well on windows 10 (64) with java 64-bit