The Falling of Hell's Army

In an ulterior universe where the world is stuck in the middle ages, the only way to become king and marry the princess of the leading kingdom Romalana, you must go through a sacred ritual that has been passed down from centuries that puts your state of mind into an alternate reality. One where you are in a war to protect your kingdom as a king, from Satan's army and the only way to do so is to kill him. Our story begins with a young man, barely reaching the age of 20, Leo, who challenge the king to this dreaded to test in order to take his daughter's hand in marriage to prove his worthiness.