The scenario is set in 1718, in a world where the Roman Empire never fell, but had to share the Mediterranean with the Ottoman Turks, who gradually settle themselves in Anatolia and conquer parts of the Persian Empire. The Russian Empire in the north cuts the Ottoman Empire in two, so the Turkestan Caliphate is formed. The Arabs have founded their own sultanate in the Ottoman sphere. Judea is a heavily armed, neutral state sandwiched between the empires. The Axumite Empire has established ties with the Romans and is a loyal ally. The Kanem Empire holds on to itself and is happy to trade with all. Together the empires have started exploring and colonizing the Americas (north and south Vesperia in this TL) and Africa. However, the Ottomans and the Romans still look at themselves threateningly across the Bosphorus.
This has excalated to an invasion of the Axumite Empire from the ottoman colony of Kush. The Turks quickly sweep in, conquering town after town in the poorly defended northern regions. Kassala is taken on June 8th, and on June 12th they are within 100 km of Axum, but some troops manage to sack the city two days later. Meanwhile, the Arabs land on the Tadjouran coast, occupying the city and its surroundings. A few days later they invade the island of Socotra, given by the Romans to the Axumites just a few years before. At first, the Turk-Arab coalition ignores the port of Ptolemais Theron, a Roman exclave, but on June 14th some troops manage to seize the city anyway.
News of the invasion of Ptolemais and their Ethiopian ally arrive to Rome. They initially created a naval blockade along with the Judeans on both exits of the Channel of the Gods (AH-analogue of the Suex Canal), at which the Ottomans responded with a blockade on the Bosphorus. After the invasion of Ptolemais, however, the Romans decide to respond with a show of force, attacking through the Nile into the Kush colony, initially capturing the city of Port Kush (known by the Romans as Berenice) on June 16th.
Then, they continue to advance into the desert, with the intent of capitulating the Turk forces in the colonial capital Dunqulah.
The Ottoman forces start to retreat in the occupied territory, losing momentum. Without further support, the Arabs are quickly pushed out from Tadjoura and Socotra on June 17th, and Kassala is retaken on June 21st. Troops are recalled to Dunqulah and Khartoum to deal with the Romans and Axumites respectively. They gain the upper hand, and defeat the Ottomans on July 7th 1718. No battles nor invasions take place in Europe, nor on the shores of the Bosphorus, due to a distinct fear of both sides to destroy each other. The naval blockades lasted till the sign of a peace treaty, blocking the major trade routes with India, Malaysia and Ruthenia (Russia).
A new non-aggression pact is signed between Rome, Istambul and Axum. Ships sail the Bosphorus and the Red Sea once again.
Flags are from Wikipedia and Reddit, and are from left to right: Roman Empire, Ottoman Empire, Persian Empire, Axumite Empire, Arabian Sultanate, Judea, Turkestan, Kanem Empire
Further maps of this scenario are coming very soon, showing more in detail the various battles and invasions