Here's my idea:

Setup a simultaenous 40k tt experience with a game of Only War (Or rpg line similar: Dark Heresy, Rogue Trader, etc).

Using Vassal and a once a week narrative campaign setting, using the results of the game to dictate the playing environment for a weekly RP group via Roll20.

I'd need to do alot of prep work, and right now i'm toying with the viability of the idea. I'd like to ask the OW community here if anyone has done anything similar (or integrated other lines, like BFG, etc) to suppliment the gaming experience.

Sort of sounds vaguely similar to an idea I read about years ago, where people dual-played TT and BFG. Success in the space theater could directly impact how many of your units might be available for the ground war, and might allow other assets, as well (an orbital strike, +1 to Reserve rolls, etc.) Sort of a shame BFG went and died.

Sort of weird thing with this, though. In my mind, players are often going to be outnumbered, and taking advantage of being PCs to make up for it. TT is more requiring of you both having roughly equal, if possibly significantly divergent armies. I don't expect to play 1500pt IG against 2000pt Orks; not happy odds. Maybe I'm just looking at this from a weird angle.

I think something like this is fairly popular in a lot of games that have a presence on multiple "layers" of a setting. In terms of 40k, I have heard of events where people linked BFG and 40k TT, with both games being played simultaneously and affecting one another. And then of course there is the Planetary Empires ruleset from GW, which directly provides a strategic background and narrative for linked campaign play.

In terms of P&P RPGs, there is the transition between the Battletech tabletop and the A Time of War RPG, which even provides official rules for switching back and forth in "scope".

I don't believe there is a lot you can actually do wrong if you consider only the basics. Any encounter on the tabletop is a small story in its own right, and thus also serves as a potential backdrop for a roleplaying session. The easiest way would be to just have the tabletop influence the RPG, but if you want to invest some more work into such a campaign, you could have both games influence each other in a continuous back-and-forth, with the RPG group's actions having a small yet recognisable effect on the basics of the next TT battle (such as a useful bridge having been destroyed, or one side suffering from delayed reinforcements, etc).

That being said, since RPG sessions tend to assume the success of the player group and are more about the "getting there" rather than "winning the game", perhaps it would be a better idea to just have the tabletop provide the narrative and leave it at that.

[edit] I see venkelos may have heard of the same event/s.

I don't really think I'd go with the stacked sidings on the TT side of it. The forces may be overall uneven narratively speaking, but the key missions would be fair with opportunities from the campaign structure of the TT side to get boons and benefits from playing the long game.

The only buzzkill I foresee is the notion of "winning" the TT exercise becoming the primary objective in favor of any RP experience upon which it would be based. You might consider alternating each phase of the TT game- friendly Movement, then enemy Movement, then friendly shooting, and so on- so that turns in the TT environment are less likely to "swing" severely. This would make for a much longer game, but lend itself nicely to integrating an RP attachment to the ponderously shifting tides of battle.

I did something very similar many years ago (3rd Edition 40K)...

Players on the TT each nominated one unit, and rolled d20 for initiative- whomever had the higher initiative moved their nominated unit first, followed by the lower initiative unit. Each unit would complete both a Movement and a Shooting phase in its initiative, then once all units had moved and resolved any shooting the process of nominating units began again for Close Combat (for any units within charge distance).

It made for a longer game, but it changed the tactic dynamics significantly. We played probably two dozen games in that manner, though each one lasted into the early evenings. Perhaps just one Turn of TT could be done each week, with the PCs being required to respond to the unfolding TT events in attempts to turn the balance of particular engagements, or to salvage resources from failed maneuvers.

Taking into account the responses, I think i'm going to go with a module similar to this:

Tabletop games will be played once per week on a map campaign. The narrative of the battles will also set the scenes for the rpg element in terms of territories in possession, safe zones, and hostile terrotories.

The game each week will be played from the player's regiments versus me, to generate the results, and each week a different player will be up.

The rpg element of only war will be set with different objectives for the most part, and only receive inclimental or assistance based on the elements of the map. As the influx of troops and enemies per area will be judged by the tt results, it will provide a constantly flowing battle line.

If the players are unable to keep the enemy forces from advancing, then in the rpg side things will get more and more desperate (narrative wise).

I think that method would keep the gamey aspects restricted to the tt sessions, while giving the players an incentive to try to 'beat' the gm during TT to make their RP equivilents more likely to survive their missions.

Any thoughts on that?

Well, it all comes down to the interplay of both aspects and how much they affect each other. Also as a TT we have quite a different situation on the board where the TT Meta dictates about balance etc. A Only War regiment with some nice taste to it could make a horrible TT Army and things get even much much worse if you start with different army values.

The danger is that the entire game gets more focues about the TT for it might have the biggest impact on the campaign overall and that some kind of min/maxing is going on to have the best impact on the board. Also your players might loose the feeling to be their own masters in the RPG and to forge their own fate when it all comes down to a weekly TT game.

It is true that the GM was always the story teller but this might increase that kind of effect even more to a degree where the actual RP gets less and less important.

Also I imagine it quite difficult to balance the interplay to prevent some pretty nasty vicious cycle. I agree that such a thing might be alternatively interesting but if they fail TT battles because of failed RP missions and fail RP Mission because of lost TT battles it could become quite dull for they lack the motivation to go through a several hours taking TT battle just to loose again or minimize the losses. After all the TT is about winning and a fragile balance that might get utterly destroyed if not integrated with a good design into something different.

It would be easier to discuss this if you could offer some specific examples how you imagine these two components to interact with each other for it would be quite devastating to say: "You lost that RP destruction mission, now your enemy army is 200 Points stronger." or "You did not spot the mobilization of the enemy and now he can field more units faster"

sure. This idea is definitely something I want to work on for ahwile before implenting. Ideally, here's an example of how I'd want the 'spirit' of the mechanics to work.

Tabletop game (on monday):

Setup includes a unique campaign map, seperate from the individual 'table tops' we know and love. During each week (or phase, as I'll refer to them), the enemy/friendly elements make their moves. An example map drawn from a quick google search:

I'd keep the map on a Roll20 page to account for positioning tracking. One note: I'd color code the areas into friendly, contested, and hostile by highlight colors.

When a week's move envokes a battle by an enemy or allied marker 'invading' a contested or hostile territory, we play it out the tt game. The result either removes that marker from the map for either the enemy or the ally.

There will be some special locations like Manufactorum, or a city space port. When these elements are captured by an enemy they envoke a minor penalty to logistics and vice versa. Here's a spread sheet of some early concepts I'm brewing

Munitions Manufactora: -20 on all SP ammunition for logistics rolls. -10 on all [Planet Pattern] weapons from this region for logistic rolls. If captured by friendly forces, the penalties become bonuses. Uncontested is straight modifiers.

Spaceport: If captured by an enemy tile: Successful logistic rolls don't arrive to the players. They have to get aerial drops in game, and risk getting spotted by the enemy troops. If captured by an ally: The players logistic rolls gain +20 circumstantial modifier.

RP Session:

So using the capture of the spaceport as an example:

The soldiers are moving with a vanguard towards a city to liberate it from an enemy force. They've received word that the principle route for supplies has been compromised, and getting supplies will be tough. They've been given these instructions from the encrypted vox battlenet by command.

When they arrive, they do their thing and we rp that scenario completely. At the end of the session, they make their logistic rolls for next session and then get the penalty of having to rp finding their aerial dropped supplies and risking getting spotted by enemy scouts.

capture of the city in the above scenario by the rp host would mean that the warzone map is updated likewise

I hope this is an indicative post of what I'm hoping to set up.