Which is the original "L’Abbaye des morts" game?

The game L’Abbaye des morts can be found implemented for many retro and modern systems. For example:

• Commodore 64
• Sega
• ZX Spectrum

It is visible that the game is implemented by different people or companies and that some of the ports are commercial. This makes me wonder which is the original game and who owns the right to it. Also, is it legal to create a commercial port for someone’s else game?