Crisis Core is a prequel to Final Fantasy VII and focuses on the character Zack Fair. The story follows Zack as he is assigned to look for a missing military officer, Genesis Rhapsodos, and intersects with the backstory to Final Fantasy VII, where protagonist Cloud Strife knew Zack and took up aspects of his personality and backstory as the result of a mental breakdown. Crisis Core was well-received, but had a limited audience due to only being available on the PlayStation Portable.
The remake, Crisis Core: Final Fantasy VII Reunion, will be available on PlayStation, PC and Xbox later this year.
Square have also confirmed that the Final Fantasy VII Remake project will now span three games, plus possible expansions. Final Fantasy VII Remake was released in 2020, followed by Final Fantasy VII Remake Intergrade in 2021 (including an expansion focused on the character of Yuffie). The second part, Final Fantasy VII Rebirth, will be released in late 2023 and will focus on the adventures of Cloud and his team after they leave the city of Midgar.
An as-yet untitled third part will follow and wrap up the project, presumably around 2026. The next mainline game in the series, Final Fantasy XVI, is due for release in summer 2023.