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nightcraw1er.488: Cool, good news. In this age where everything seem to stop working except on bleeding edge, highly builds, compatibility is a big problem. Especially as all these games are XP or before era.
The lack of support for WinXP was the one reason keeping me from considering this. Plenty of other developers out there (including one-man shops) offering support for older versions (even 9x/ME). Lack of support from MS means no further updates which should really make support easier (no likelihood of having to make emergency changes to accommodate a new Windows update for instance).
HiddenAsbestos: Grid Cartographer is 7 years old today. The project began on these forums, thank you all for the support and encouragement over the years!
morrowslant: GC4 is a great utility tool.
Link to the Grid Cartographer 4 website in the OP is slightly outdated though, you may want to edit/update the link.
thanks! and I updated the op :)

As for Windows XP, the compiler I'm using (Visual Studio 2017) makes executables that literally don't run at all on Windows XP any more. Let alone the fact that XP is predominately 32-bit and GC has been 64-bit for a long while. You need Windows 10 to run it, sorry.
HiddenAsbestos: ...the compiler I'm using (Visual Studio 2017) makes executables that literally don't run at all on Windows XP any more...
If you're generating 32-bit code, then it's a two byte adjustment to get it working on XP (unless you're using DLL functions only implemented from Vista onwards - even then these can often be worked around).

64-bit code is another matter entirely of course. But exactly what part of an application generating maps for (principally DOS-era) games requires >2GB RAM space? Particularly since Campaign Cartographer, a far more mature (and seemingly better featured) map creator requires just 256MB.