Mare Nostrum is a multiplayer team-based first-person action video game by American developer Sandstorm Productions, created as a total conversion modification of Red Orchestra: Ostfront 41-45.

The overall aim of the modification is to incorporate the African, Mediterranean and Middle East theatres of World War II as a supplement to the Red Orchestra: Ostfront 41-45 title.

[2] The Mare Nostrum game project is current subdivided into two phases which reflects the original merger.

The second, unreleased, phase is titled 'Mare Nostrum: Campagna Italiana 43-45', and will encompass actions in and around Sicily and main land Italy.

[7] Although the 1.2 release was considered a playable product, there were issues building an online player base.