Hey guys. I'm working on a really big campaign with some ideas that I have a LOT of trouble integrating.

Story introduction:

As suggested in the title, it will be set in the year 50k. The Galaxy is being ripped apart by the "Terra singularity" a man-made black hole with a mass of 100 million solar masses. The Eldar are extinct save for but one, who resides alone in the last craftworld. Yet some Dark Eldar still linger, they too are very few in number. The imperium of man is shattered as their connection to the Emperor is lost, as it is thought that Earth was swallowed up by the Terra Singularity, and indeed this cosmic creation was formed in our solar system. While the destruction of the Galaxy as now yet completed, as the Gravity from the black hole has yet to reach the entire galaxy, impending doom is upon all, and even the Chaos God's have discovered fear, spawned from this creation of man. Though the Terra singularity was actually a massive failure, for the black hole was meant to swallow up the entire universe and rebirth it in a second big bang. This group of brilliant, yet insane scientists call themselves the M.O.P. or Mothers of Purity, as they believe that the universe is so full of filth, destruction, and suffering, that the only option is to see to it's rebirth.

Tyranids have been infected with a M.O.P. created virus that rots their brain, driving them insane and makes them kill all who are in their line of sight, including other tyranids. Some Tyranids are yet unaffected, and the hive mind contemplates how to save the universes biomass.

Necrons have been assimilated by the M.O.P. and their technology utilized to advance their goals.

Tao are under threat of extinction, but can still be seen wandering the galaxy.

Orc still luv da fightin and don't really understand or care about whats going on. (Though that may change if they figure out that they won't be able to do da fightin no more cuz o big humie black suckers)

Ideas for gameplay:

The idea is, that this is such a great threat, that alliances are forged that before could NEVER be possible, such as Chaos, Tao, Dark Eldar, Orcs, and even Tyranids teaming up with branches of the imperium. The group will be the elite team that tries to stop the M.O.P. before they can create a black hole big enough to suck up the entire universe.

As you can imagine, when I brought this idea of these alliances up, there was a LOT of nay-saying on the part of my more lore savvy friends of the 40k universe. There is also the issue with mechanics. If someone wanted to play a Tyranid, how would it balance out in combat vs a space marine, how can I still make combat fun with such powerful party members? What kinds of missions should I write that would make sense for this roustabout group of aliens and men?

Basically, how do I get this idea to work?

Hey guys. I'm working on a really big campaign with some ideas that I have a LOT of trouble integrating.

Story introduction:

As suggested in the title, it will be set in the year 50k. The Galaxy is being ripped apart by the "Terra singularity" a man-made black hole with a mass of 100 million solar masses. The Eldar are extinct save for but one, who resides alone in the last craftworld. Yet some Dark Eldar still linger, they too are very few in number. The imperium of man is shattered as their connection to the Emperor is lost, as it is thought that Earth was swallowed up by the Terra Singularity, and indeed this cosmic creation was formed in our solar system. While the destruction of the Galaxy as now yet completed, as the Gravity from the black hole has yet to reach the entire galaxy, impending doom is upon all, and even the Chaos God's have discovered fear, spawned from this creation of man. Though the Terra singularity was actually a massive failure, for the black hole was meant to swallow up the entire universe and rebirth it in a second big bang. This group of brilliant, yet insane scientists call themselves the M.O.P. or Mothers of Purity, as they believe that the universe is so full of filth, destruction, and suffering, that the only option is to see to it's rebirth.

Tyranids have been infected with a M.O.P. created virus that rots their brain, driving them insane and makes them kill all who are in their line of sight, including other tyranids. Some Tyranids are yet unaffected, and the hive mind contemplates how to save the universes biomass.

Necrons have been assimilated by the M.O.P. and their technology utilized to advance their goals.

Tao are under threat of extinction, but can still be seen wandering the galaxy.

Orc still luv da fightin and don't really understand or care about whats going on. (Though that may change if they figure out that they won't be able to do da fightin no more cuz o big humie black suckers)

Ideas for gameplay:

The idea is, that this is such a great threat, that alliances are forged that before could NEVER be possible, such as Chaos, Tao, Dark Eldar, Orcs, and even Tyranids teaming up with branches of the imperium. The group will be the elite team that tries to stop the M.O.P. before they can create a black hole big enough to suck up the entire universe.

As you can imagine, when I brought this idea of these alliances up, there was a LOT of nay-saying on the part of my more lore savvy friends of the 40k universe. There is also the issue with mechanics. If someone wanted to play a Tyranid, how would it balance out in combat vs a space marine, how can I still make combat fun with such powerful party members? What kinds of missions should I write that would make sense for this roustabout group of aliens and men?

Basically, how do I get this idea to work?

Its very different... i will give you that... I can understand why there are a lot of the nay-saying.. Especially "assimlation of the necrons"

Personally, i don't think the 'nids will team up. Not because it might not benefit them, but because the hivemind aren't "human" it has a certain understanding, but it is fundamentally so different from us... I believe one of the kill-team novels is a good starting point (unfortunately i can't really what its called)... might as well try to team up with a scorpion...

BUT, all that aside, i do personally think that the story is innovative and the idea of different races teaming up is awesome

You can look to the third Greyknight novel for inspiration..

In relation to game mechanic.. when yes its going to be quite an issue... however i would simply create a few "races" like with the space marines... like tyranid warrior, some jumping, bonus to str and toughness, lictor and ravener... Elder are likely to have very high agi...likewise could be done... though i am unsure exactly how do it... i would suggest you work with your players, and make a class that does what they want while still being balanced...