A plot could involve a conflict where the Covenant from Halo somehow gets involved in the Clone Wars. The Clone troopers and the Jedi would have to figure out how to fight this new and strange enemy. The story could explore how the different powers and abilities in both universes interact. For example, the Force versus the Spartans' enhanced physical abilities. It could also show how the Jedi Council reacts to the arrival of these unknown warriors from another dimension.
One idea could be to cross Halo Wars with another popular sci - fi franchise like Star Trek. Imagine the Covenant and the Federation having to deal with each other. Another idea is to have a crossover with a fantasy world, like Lord of the Rings. Maybe the Spartans end up in Middle - earth fighting alongside the elves and dwarves against a new threat that has elements of the Flood. A third idea could be a crossover with a post - apocalyptic world. The Halo Wars units could be trying to survive in a world full of mutants and scarce resources.
One interesting plot idea could be the Spartans from Halo Wars 2 teaming up with the Jedi from Star Wars. Imagine the Spartans' combat skills combined with the Jedi's use of the Force. They could fight against a common enemy, like a powerful Sith Lord who has somehow got hold of Covenant technology.
The Covenant's energy weapons and their unique alien abilities could mix with the Star Wars technology and Force powers in various ways. The Grunts could be like the Ewoks in terms of being small but fierce when combined with the right support. The Elites' combat skills might be on par with some of the Star Wars bounty hunters, and together they could form an interesting team.
One interesting concept could be the Spartans from Halo interacting with the Jedi in Star Wars. Imagine a Spartan being trained in the ways of the Force. Another concept might be the Covenant technology being used in the Star Wars universe, like their energy weapons in the hands of the Sith or the Rebels. And also, the Flood from Halo could be a terrifying new threat in the Star Wars galaxy.
Perhaps a group of Spartans could be sent on a mission in the Star Wars galaxy. They get caught in the middle of the Clone Wars and have to decide which side to support. Their unique upbringing and loyalty to the UNSC would create an interesting dynamic as they interact with the political and military factions in Star Wars.
Begin by choosing the other universe you want to cross 'halo wars' with. Let's say you choose a fantasy universe. Next, decide on the main conflict. Will it be a war between the Covenant and the fantasy races? Or a common enemy that they have to face together? Then, create your characters. You can take existing Halo Wars characters and give them new roles in this crossover. For example, the Spartans could be seen as mythical warriors in the fantasy world. Start writing short scenes to build up the story and don't worry too much about making it perfect at first.
One idea could be that Master Chief somehow gets transported to the Star Wars Rebels universe. He could team up with the Ghost crew. His advanced combat skills and Spartan armor would be a huge asset against the Empire. Maybe he'd share his knowledge of advanced weaponry with the rebels.
One idea could be that the Spartans from Halo are sent through a wormhole and end up in the Star Wars galaxy. They could then get involved in the Clone Wars, with their advanced technology and combat skills being a huge asset or a source of great confusion among the different factions. Maybe they team up with the Jedi at first, but then some misunderstandings occur due to their different ways of handling situations.
One possible plot could be that Master Chief somehow gets transported to the Star Wars Rebels universe. He teams up with the rebels to fight against the Empire. His advanced armor and combat skills would be a great asset. Maybe he has to face off against Imperial Inquisitors and uses his Spartan training to outwit them.