Starting with Visual Studio RC, Visual Studio 2015 appears to no longer support the Office Add-In project types from Visual Studio Tools for Office (VSTO). Lots of googlin' and questions to PMs in the MS blogs have revealed no useful information; but perhaps other in the community know more. Opening a VSTO project yield "(incompatible)". so:
I don't have 2013 anymore because i wiped that machine...
Do you have the Community edition of VS installed?
Try to install https://aka.ms/getlatestofficedevtools .