It's just a suggestion, though I want an Assassin's Creed game set in the Roman Empire, 217-330 AD.
What would I like to see in this game?
-I want to see Rome in all its splendor and ancient glory, with all the monuments built. The fact that I want it to be set in the third century is because then was built the Baths of Caracalla, plus the Colosseum, the Parthenon, the Baths of Diocletian, Domus Aurea, Basilica of Maxentius, Cloaca Maxima, Circus Maximus, Mausoleum of Augustus and Trajan's Market .....and Colossus of Nero.
-I want it to happen especially between the 3rd and 4th century because then the Roman Empire went through a serious crisis.
-the game could begin with the assassination of Caracalla, a member of the Order of the Ancients, by a praetorian who could be a member of the Order of Assassins. The story will include civil wars, peasant rebellions, political instability, plagues, debasement of currency, and economic depression, connections with Germanic mercenaries and the creation of federations.
-the culmination will be the division of the empire into the Gallic Empire, the Palmyrene Empire the Italian Empire proper.
-the main story will end with the restoration of the empire and the assassination of Aurelian
-the story could be extended with a DLC about Constantine the Great and the officialization of Christianity
-the game could include a family of assassins, with mechanics inspired by the Watch Dogs Legion in which you recruit assassins. Assassins can be killed, they can be promoted, they fall in love, make kids, create families, construct their house, can grow old , and die. Yes, it will be difficult to attach to a particular character. But I liked the Watch Dogs Legion recruitment system and I would like to see it implemented in an Assassin's Creed. The game takes place over a period of 100 years, so we could have many characters to attach to. We could recruit assassins from all social classes.
-I would like to explore all the provinces of the Roman Empire: Rome and other large cities in the Italian peninsula , Gallia (France + Belgium), Hispania (Spain and Portugal), Raetia Noricum (Switzerland ), Thrace (Bulgaria), Asia Minor (Turkey), Syria and Judea, Africa Proconsularis, Mauretania (Tunisia and Morocco), Dacia (Romania), Dalmatia (Serbia), Mesopotamia (Iraq), Armenia, Egypt with all regions from Assassin's Creed Origins, Greece and Macedonia with all the city-states and regions from the Assassin's Creed Odyssey, southern England from the Assassin's Creed Valhalla. With great cities included like Antioch, Ravenna, Ephesus, Carthage, Londinium, Alexandria, Amorium, Athens, Mediolanum, Ulpia Traiana Sarmizegetusa , Lutetia Parisiorum, Thessalonika and Mystras. Even the Jerusalem with the ruins of the Temple.
- I want to visit/revisit all the ancient wonders of the world : The Great Pyramid of Giza with the Sphinx, the Lighthouse of Alexandria, the Great Library of Egypt, the Statue of Zeus and the Pantheon in Greece, the Mausoleum of Halicarnassus in Asia Minor, the Suspended Gardens of Babylon, and even the ruins of the Colossus of Rhodes, with his head down besides his ripped legs+ Hadrian Wall in England.
-I want to customize a roman house (Villa) and even work for money (dennarii) when I don't do assassination missions, like in Skyrim .
-I could send an assassin to get involved in a civil war between generals claiming the throne (to decide who could be emperor) ,or a battle with germanic invaders or a siege. And to buy, instruct, equip and prepare your own legion.