Play Diplomacy Online

I looked in the variants section but could not find a description. What are the rules/map like?

The rules are the same as the standard game and the map is very similar.
Have a look at an archived Milan game for full map, but the only real difference is an extra territory in the Milan area. Piedmont/Venice becomes Savoy/Milan/Venetia, with Milan being the SC instead of Venice.

The concept of the variant is to liberate Austria and Italy from the Venice/Trieste stand-off in 1901 by allowing both to have a buffer between their home center and enemy units. I have not played the variant, though, so I don't know how it turns out in practice.