Akhenaten

Akhenaten is an open-source reimplementation of the classic city-builder Pharaoh (1999), including Cleopatra expansion support. It aims for compatibility with original savegames and campaign missions on modern systems.

You need a legal copy of Pharaoh (and Cleopatra, if used). Pass the Pharaoh install directory as the last command-line argument, or grant the Flatpak access to that folder (for example via Flatseal) so the in-app folder picker can see it. Portal-based folder selection is planned.