We all know classic diplomacy, the classic variant, which is what the game was when it was first created and marketed as a physical board game.
With online play and the advent of variants we see plenty of new features and generally completely ways to play. With different units and special rules in some games.
But honestly the strongest feature online play has is that there is no paper. The ease with which you can file orders, and handle the map and orders is infinitely superior to physic diplomacy. The fact that it was such a chore to process orders in physical diplomacy is what I believe limited it to what it is now, a very well balanced, map in which you start with three/four units. Because if more units were in play throughout the game, it would be nearly impossible to facilitate the game physically.
As such, newer variants follow very similar setups to the original (well perhaps except for the annoying tendencies for new variants to have many open supply centers for every single country).
But what I would like to see with the fact that online diplomacy isn't constrained with the difficulty of processing many orders, is variants in which countries start with 20+ units, a widely split board, and perhaps special rules allowing all units to move 2 spaces/have two actions as can be seen in specific variants right now.
This would reflect a greater amount of tactile strategy. Although the fact that more tactile strategy would be involved could perhaps lessen the importance and focus on diplomacy and negotiations, due to that fact that you would be more able, if capable and efficient, to defeat greater odds without the aid or misdirection of others.
It could be balanced so that much focus stays on relations through close supply centers and what not, but generally the focus of the game would shift, which isn't really a problem, it's just a different way to play, and would be interesting to have one or two games going.
A few changes would need to be made as well although. One thing, which I think normal diplomacy may also benefit from, is single countries only get a fraction of units for the supply centers they hold, and this fraction is smaller the more supply centers are controlled. This would highlight the efficiency of smaller countries, and offset the unfairness that we see in larger maps such as WWIV, where larger countries will have vast unthreatened interiors so they can focus all their forces at the edges of their empire, thus making them much more effective for having just as many supply centers as other countries that are smaller and have supply centers that are almost exclusively close to borders. This would likely be more prevalent a problem with the increased emphasis on tactics, and a system like this would help to give an advantage to those who use diplomacy and alliances, rather than just relying on numbers.
Secondly, with how many more supply centers and units an ultra high unit game would have supply centers would make more sense not to be a single territory, but rather be a collection of territories. The supply center would only change hands once one country controlled all the territories, then it, and it's benefits would shift to that country.
This would also say, that since supply centers aren't single territories, and with the high amount of units, one "supply center" wouldn't provide one unit, but rather a larger amount of supply points (I say supply points since earlier I proposed a ratio.
Lastly, since armies can move two, fleets would need to be buffed, since they do not have access to two territories inland, but only the coast. They could be buffed with perhaps being able to convoy and support move in one turn, or other things. Their importance may be buffed normally through the fact that so many would be needed to convoy. It may be better simply to change it so that a fleet can hold an army rather than having to set up a convoy chain.
With holding armies further things could be instituted such as an easier process with which to destroy units, perhaps even the destruction and burning of occupied supply centers, but this is just spitballing.
Anyways, yeah. I would try to make this variant if I had the time/knew how to make variants.