I have a certain hankering to go back to the Spanish Civil War again, and I've had a long standing design for a scenario covering the Battle of the Jarama in 1937. Somewhere or other I found a very detailed OB which actually listed the battalion level composition of the Nationalist brigades as well as the artillery holdings for both sides rather than the vague acounts you find in Thomas, Beevor et al. Originally I thought I'd do it using Megablitz, in a similar manner to the 1938 Battle of the Ebro game I ran years ago, but MB doesn't really work in a remote multiplayer environment as it relies on hidden strength points, hidden order chits and hidden combat results and I can't think of a way of modding it for remote play without breaking many of its core systems.
It was easy enough to tweak OP14 into something more suitable for 1936 though, by simply beefing up the armour and air support rules and modifying the ground scale a bit to represent the rather more dispersed units and the timescale to allow for the increased ground scale. Job done I thought, but then came the interesting experience of seeing how it actually played out.