Hello jimkehn:
That’s definitely very interesting with the Gunslinger engine. It does look very familiar to that of the VASL, in fact the first sentence on the VASL website says: “VASL is the adaptation of the VASSAL engine to the ASL game system”
http://www.vasl.org/ So I suspect the same designers may have worked on both versions maybe.
But it’s good, I’m very familiar with the vassal engine (as far as VASL) so I’m sure it would work very well for Gunslinger, or other similar games of that genre which use geomorphic boards such as Firefight, MBT, others I can’t think of right off-hand (Panzerblitz/Panzerleader).