Grunt said:
If the numbers are really as horrible as the fluff speculates they are, the galaxy is fucked.
If there really are as many hive-fleets as there are worlds in the galaxy, then the game is over. Completely, absolutely. Even more so because the new Planetstrike book confirmed that the tyranids can devour even orc spores.
Thing is also healing the emperor would be a boost yes...but it would also mean major disturbances, with revolutions, massacres and genocides day after day....eh...even more than is the norm I mean.
Even if the number of hive fleets (That is, the big invasion forces that there've been... three of? Kraken, Behemoth and Leviathan, with maybe a fourth way back when) is an order of magnitude less, everyone's in trouble in a straight-up fight as-is.
So... there needs to be game-changers of various sorts.
1) Technological/Naval approach. If you can bring the Imperium to the technological level of the heights of human technology of the past, then you've got the potential for a very solid defense against the fleets before they hit dirt.
There are three components involved in the naval approaches; first of all, detection. You need a way to detect the present and future position of hive fleet components - if you can track them, you can ambush them. Aside from possible FTL sensory handwavium, there's probably a decent way to do this by sensing the presence and strength of the hive-mind (ala how astropaths can know when a hive fleet is incoming by the warp-shadow it casts). The better your detection, the easier it is to perform the later steps.
Second of all, interception. Warp drive, as it stands, is somewhat unreliable as to how fast it gets you places. A more consistent or faster drive would help coordination; the better you can coordinate, the more forces you can bring to bear upon a given hive fleet segment and the faster you can move the more space a given set of ships can cover. Better detection would allow you to intercept earlier and with greater force.
Last of all, elimination. It's pretty likely that a solid archeotech base (with modern-ship numbers) with some xeno additions could make mincemeat of pretty significantly sized hive-fleet segments.
Overall, it's theoretically possible; the Imperium has a huge logistical base, with the numbers to crew fleets and the manufactories to turn out materials. All that is needed is the knowledge (say, in the form of a couple of intact STCs) and the social control (you'd need the Emperor, really).
2) "Heal the Emperor". In theory this gives the Imperium a really strong central will, given a few years for the big guy to consolidate and purge. His psychic capabilities are enormous, as are his mental capabilities; if anyone can find a way to turn something like the beacon into a Hivefleet-detecting radar station, he probably can. He probably also has a pretty significant amount of knowledge at his disposal, allowing the archeotech option to a greater or lesser extent.
3) The "Untouchable" approach. This is predicated on how psychic blanks affect the hivemind (they more or less shut it down). Given a way of performing interstellar-range telepathic jamming, it's quite possible to ward any Imperial systems against hive-fleets. As the fleets are always seeking biomass, if you can prevent them from being able to enter the vicinity of biomass-bearing planets, you more or less form a defensive win. If the method is ship-transportable (even with a shortened range), then you probably have a way to guarantee the death of any hive-fleet segments outside the protected area you can find. And, even better, all the species as a whole knows is that communication from a particular piece completely stopped... You might need to couple this method with a way to detect and elimination genestealer infestations, depending on the nature of the interference.
On the whole, the actual number of hive fleets is not as much of an issue. If you can find a way to reliably defeat them, then the Tyrannid species is going to probably look elsewhere for biomass.
Sooo... plan, assuming the social directional capability exists:
1) Develop a consistent method for jamming the telepathic hivemind communication on a planetary level. This could be a combination of warpcraft, technological research (geller fields and force weapons indicate that technology can affect warp and psychic powers), Eldar wraithbone technology... whatever works. Considering the existence of alpha+ psykers and assorted phenomenon, this is probably not out of the question. The requirements: It needs to be able to cover the whole planet (and maybe a bit around it), be reliable, consistent and more or less indefinitely sustainable. Bonus requirement: It's ship-portable for fleet action.
2) Create a long-range hive mind detection capability so fleets and traders know where the tyrannids are; the former for search-and-destroy and the latter to avoid.
3) Cover the Imperium worlds with the technology.
4) Use the technology as leverage to dominate the Eldar and Tau. Orks aren't likely to care, so just let them have fun with their new playmates.
That's the best bet I can find - use the hive mind as the weak point to attack.
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