Digimon World 1 was released for the original PlayStation (PS1) console.
While there are emulators available for the PS1, like ePSXe, PCSX2, and RetroArch, they cannot run Digimon World 1. This is because Digimon World 1 utilizes a specific hardware component called the "SCPH-1001" that is unique to the original PS1. This hardware component is not emulated by current PS1 emulators.
Therefore, if you want to play Digimon World 1, you need to acquire a physical PS1 console and a copy of the game.