MTL - EVE: Start a Space Station - Chapter 580 Armageddon - Revelation

Our protagonist was a Mexican who died on a flight, when he woke up he found Apollo who reincarnated him as the grandson of Gaius Octavian Turino (Augustus) the first Roman emperor, having a mission in hand to conquer the New World to save the Roman polytheist world and his existence.

In an alternate timeline of Warhammer 30k, the Emperor of Mankind discovers the Independence Cluster, a group of technologically advanced worlds that have preserved Dark Age of Technology knowledge. Here, He encounters His first found Primarch, Franklin Valorian, known as the Symbol of Liberty.The charismatic and humorous Valorian, standing 15 feet tall, meets the Emperor with a mix of curiosity and irreverence. Unlike others, Valorian sees the Emperor as a powerful but regular man with a greater purpose, akin to a superhero.

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates