Nothing too out of ordinary you could expect from such war. But first of all the "basic" map idea would be set into the scenes of Taipale-Terenttilä region (having the russians cross the river and open fields with human waves) and you could all relate to your favorite Winter War movie. Basic finns sitting in trenches and russians throwing everything they have against them. Simple idea, difficult to get the russians running headlessly towards certain doom. Oh well, that happened in FinnWars too, I guess we could have it in FH2 aswell.
This.
Ideas: have the Soviet initial uncap spawn be in OOB area, with a "time to punish" timer set so that one has just enough time to run away from it towards the Finnish trenches - once they are out of OOB, they are out in the open (on the icy river or at least the opposite riverbank) so they pretty much have to run towards Finnish positions in order to survive. Having a few "dummy spawns" in shell craters on the Finnish riverbank would give more incentive to charge forth -- however, the same craters would also be OOB, preventing taking shelter in those. Give the Soviets 3+ arty pieces but only a couple of T-26's and OT-130/133's - if at all. The Finns should have at least 1-2 artillery pieces as well, but would mostly rely on MGs (and maybe L-39's or AT guns, if Soviets have tanks) for support.
Second idea is to have the famous battle of Raate road with a twist. Russians are stuck in the middle of the thick forests on a very narrow road that twists and turns like a snake. Finns can maneuver within the forest and attack the russians from any direction. Whats the objective? Yes, theres an objective! Finns would have to destroy specific types of tanks in order to win. Imagine for example a T-26 which is either bogged down into snow, it has frozen over or its just stuck in the middle of other junk along the road... now, the turret is still in working conditions and it can still defend itself, but it cant run away from finnish infantry getting too close. So the russians have to protect these tanks, because if the finns manage to destroy them, then the finns will win. On other side of the map is another russian division who has working tanks and they try to race through the forest on that very same narrow road in order to provide much required defense against the white bandits who lurk in the snowy forest. Road would basically have several of these objective designed tanks sitting apart from each other so the russians have to divide the defense along the whole stretch.
Good idea, but *cough*Hyacinth 32*cough*. Won't work at all if the Finns have access to L-39's
Could work if the players really put an effort to prevent "suicide bombers" getting within Molotov coktail distance (one has to remember that this being a game, players WILL do stunts even Finns would not do IRL). Also, to keep the relief force on the road, most of the surrounding terrain should be OOB for the Soviets and/or so filled with obstacles (rocks, trees, tree stumps) that tanks & trucks simply couldn't advance off-road (but that wouldn't deter the infantry, where OOB would come in handy).
I think that despite the relative obscurity of Winter War, these two scenarios would attract interest also outside Finland and Russia, because the gameplay in them would be unlike in any other FH2 maps. Yes, there are "combined arms assaults" in the game, but not "human wave assaults" (not at least until Stalingrad where Rifleman kit would be a limited choice and "knife only" kit would be the standard). Yes, there is at least one objective map (which is never played anymore), but not a single "a pocket and a relief force" map.
About the other suggestions, Westerplatte looks very promising because it took place in a
very limited area so it could be modeled 1:1. Of course, it would require the Polish models, which would mean that the Invasion of Poland (from both sides) could then be included as well.