So, I have a bunch of PK books, which have been shelved since I realized I didn't have the motivation to finish full armies for scenarios for it. I've used my 20mm dudes for skirmishes, which is good.
BUT, I've played around with ideas for the PK system, alongside fantasy battles (which I lost the notes for) and science fiction.
I got the idea from 40k apocalypse "-mode" and thought to myself…Why not do an Emperors Korps game. Get a handful of models, base them together and run them as battalions on the table. A division of space marines vs. nurgle, tyranids or orks. The only limiting factor would be table space, SO just make the tanks and flying units represent a whole battalion instead of a company (saves a lot of euros!). A single transport unit would be able to carry a battalion of warriors into battle, and attach itself to the core battalion to provide AT-support.
Overwhelming damage -rule taken from OpFor to simulate whole battalions being destroyed at once.
Doesn't have to be 40k, just something to give the visual effect off the top of my head.
Take the races, and give them military doctrine as noted by the color of dice rolled for orders. Space Marines would be the "king" of battlefield when it comes to doctrine, with probably the most activations per army group.
The decorated leaders -rule will work very well with the lore of 40k, as heroes make their fighting forces more effective overall.
Since the game is called Emperors Korps, allow factions to ally with other forces of their alliance, so you'd get mixed factions, and could build lore around every battle (what's going on and why) and make it a custom campaign game: epic proportions, planet-sized campaign maps and the like.
Just a couple of ideas off the top of my head.