A possible plot could be that the god is a being of pure chakra. Naruto, with his own large amount of chakra, is seen as a potential vessel by the god. The story could revolve around Naruto trying to resist the god's possession attempts while also using the god's chakra knowledge to defeat the enemies in the 4th war. He could learn new jutsu from the god's chakra and use them against the powerful foes he faces.
Well, perhaps the god has the power to manipulate time. In the fanfiction, Naruto could accidentally stumble upon the god's time - altering abilities. He then has to figure out how to use this newfound power to his advantage in the war. For example, he might go back in time to prevent certain events that led to the start of the 4th war, all while trying to keep the god from causing more chaos.
One idea could be that the god is actually an ancient entity sealed away long ago. Naruto discovers a way to communicate with it during the chaos of the 4th war. Maybe the god offers Naruto a deal to end the war quickly but at a great cost to himself, like sacrificing his ninja way. This would create a great internal struggle for Naruto.
One idea could be exploring the backstories of minor characters during the Fourth War. For example, how the ordinary shinobi coped with the chaos and fear. Another could be a different strategy for the Allied Shinobi Forces that changes the course of the war in unexpected ways.
In a Naruto 4th Shinobi War fanfiction, we could have a plot where the Akatsuki actually had a hidden agenda that was not related to the tailed beasts at all. They could be using the chaos of the war as a distraction to perform some other dark ritual. And perhaps a young shinobi discovers this and has to race against time to stop them while also fighting in the war.
A third idea is a story centered around a shinobi who was thought to be dead but actually survived and is now trying to get back to the battlefield. Along the way, they discover secrets about the origin of the war or new jutsu that could turn the tide of the battle. They have to overcome their own physical and mental weaknesses while also evading the enemy who believes them to be dead.
Another plot idea is that Kratos somehow ends up in the Naruto universe. He could be mistaken for a powerful rogue ninja at first. His brute strength and combat skills would make him a force to be reckoned with. He might get involved in the conflicts between the ninja villages, and his no - nonsense attitude could either cause more chaos or actually help bring about peace in a rather unexpected way.
Well, perhaps in 'naruto god of war fanfiction', there's a plot where Naruto has to face a new kind of enemy that can only be defeated by combining the magic and abilities from the God of War universe with his own ninja skills. Maybe he has to journey through a realm similar to those in God of War to gain new powers or weapons. Another idea could be that Naruto teams up with a character from God of War, like Atreus, and they learn from each other's combat techniques.
One idea could be exploring the backstories of minor characters during the war. For example, how a random shinobi from a small village coped with the chaos. Another could be a what - if scenario, like what if a certain alliance was formed differently. Maybe a group of rogue ninjas decided to side with one of the major villages instead of staying neutral.
One plot idea could be Naruto facing a new threat from an old enemy who has found a way to return stronger. For example, Orochimaru could have created a new form of jutsu that allows him to possess multiple shinobi at once and Naruto has to figure out how to stop him without harming the innocent. Another idea is Naruto dealing with political unrest within the Hidden Leaf. Some clans might not be happy with his new policies regarding ninja training and he has to find a way to keep the peace. A third idea could be Naruto going on a diplomatic mission to a far - off land where they have a very different view on ninjas and he has to convince them that the Hidden Leaf means no harm.
Well, a possible plot could be that Naruto, as a god, decides to teach the next generation of ninjas in a completely new way. He might introduce them to powers and techniques that were previously unknown. For example, he could show them how to manipulate energy on a cosmic level. Also, he could be in a situation where other gods from different realms see him as a threat and try to take his powers away.
One idea could be exploring Kratos' past in more detail. For example, his early days as a Spartan warrior before the events of the main games. Maybe he had a comrade in arms that he lost, and in the fanfiction, this comrade's spirit somehow resurfaces and has a message for Kratos. Another plot could be Kratos having to face a new type of enemy that is not from Greek or Norse mythology, but from a completely different culture's pantheon, like the Egyptian gods. This would force him to adapt his fighting style and strategies.
Perhaps in this fanfiction, Luffy is transported to a realm where he has to prove himself as the God of War. He could face challenges that test not only his physical strength but also his leadership and strategic thinking, which are also important aspects of being a God of War.