If you want to right-click to open a VASSAL game file in one subdirectory with VASSAL 3.7.16, VASL 6.7.1-beta4, and a certain set of extensions, and open those in a different subdirectory with VASSAL 3.7.13, VASL 6.6.10, and a different set of extensions, VASSAL Launcher will do that for you...