Here is an overview of the game, via its official website:

About

In Assassin’s Creed Mirage, you are Basim, a cunning street thief with nightmarish visions seeking answers and justice.

Join an ancient organization and come to understand a new creed—one that will change Basim’s fate in ways he never could have imagined.

Key Features

• A Powerful Coming-of-Age Story – Discover a narrative-driven action–adventure experience that follows the transformation of a defiant young man into a refined Master Assassin with a conflicted destiny. Meet an inspiring cast of characters who will shape Basim’s destiny and may be more than what they seem…
• The Ultimate Assassin – Become the most versatile Assassin in franchise history. Parkour seamlessly through the city and leverage the largest assortment of tools to date. Get contracts at the Assassin’s bureaus, collect vital clues, and stealthily take down targets with more visceral assassinations than ever before.
• An Immersive, Reactive City – Explore a dense and vibrant city whose inhabitants react to your every move. Uncover the secrets of four unique districts, from the industrial Karkh to the lush gardens of the Round City. Discover surprising world events and interact with historical figures that shaped the Golden Age of Baghdad.
• A Tribute to an Original – Experience a modern take on the features and gameplay that have defined a franchise for 15 years. Journey to Alamut, the legendary home of the Assassins who laid the foundations of the Creed in this heartfelt homage to the game that started it all.

Characters

• Basim – Originally born in Samarra, Basim lost his mother at a young age and grew up on his own in the streets of Baghdad. Basim admires the Hidden Ones, and dreams of joining them.
• Roshan – After escaping a life of oppression, Roshan became a master assassin at the Hidden Ones’ stronghold, Alamut. Now, she takes Basim under her wing as her first true apprentice.
• More characters coming soon.

Watch the cinematic announcement trailer and a developer trailer breakdown below. View a set of screenshots at the gallery.

Cinematic World Premiere Trailer

Developer Trailer Breakdown