Well, 'Berserk' could be comparable. It has elements of a harsh world and characters fighting against the odds, similar to Apocalypse King. Also, the art style is quite distinctive.
You might want to check out 'The Walking Dead'. It's in an apocalyptic setting and features survival and human interactions in a world gone wrong, similar to what you might expect in a story like Apocalypse King.
I think 'Attack on Titan' might be somewhat similar. It has a post-apocalyptic setting and intense action.
One manga that could be similar is 'The Seven Deadly Sins' as both have epic battles and a post-apocalyptic setting.
It has an engaging plot with lots of action and adventure. The characters are well-developed and the art style is unique.
One manga similar to Fort Apocalypse could be 'Attack on Titan'. It has a post-apocalyptic setting and intense action.
One manga that could be similar is 'The 7th Stand User'. It also features a post-apocalyptic setting and unique systems for characters' powers.
" The King of Evolution " was a science fiction novel written by the immortal Ah Shui. In the novel, humans faced the danger and threat of zombies in the apocalypse. In order to survive, they embarked on an unyielding path of evolution. The plot of the novel was full of ups and downs, exciting and deeply loved by readers.
I found a recommended novel related to the king of the apocalypse. This novel was " The King of Rebirth in the End of the World ". It was an apocalyptic drama about the main character, Su Qinglan, who was reborn in the apocalypse and began her adventures. This novel contained elements such as doomsday, disaster, rebirth, and supernatural powers. Although there are no recommendations for other similar novels, this novel might meet your needs for a king's novel in the end of the world.
From the reference materials, it was known that the main character, Wang Yuan, subdued various gods after the outbreak of the apocalypse and fought against the cannibal mutated king. Later, he was known as the " ape king " and " king of hell " by the world. There was also the novel " Immortal Ape King ", which mentioned why the ancient gods were slaughtered, but did not clarify the direct connection with the apocalypse. At present, there was very little information about the Apocalyptic Ape King, and it could only be briefly described from these aspects.