We bought this rare Pong system supposably a kit on ebay - Please click on thumbnails for larger view.

Screenshot - Only One Game is built inside:

Here is what is hidden inside:

David Winter of Pong-Story (France) says:

This is the TV Tennis kit from the Elektor article published in Nov 1975: Elektor Kits.
Some extensions were also made later in 1976 to add sound and scoring.

I think it was sold as a kit. I'm not sure if it is analog or digital, it depends how the various functions communicate together.
If the signals between them is TTL (binary in the form of, for example 0V and 5V) then you can consider it digital.
If the signals are analog, then it's analog. Only the schematics can tell you, I'll check this.

5 minutes later...

I checked the schematics quickly, in fact the design is mostly digital. There may be some very small parts using analog signals but I'm not sure. Everything is made using flip-flops, NAND and other logic gates. The article on my site will show you the extension that you could build back them, like scoring, sound and automatic serve.

Jens Brinkmann sent us this scan taken out of ELO (Elektronik fuer Praxis und Hobby) magazine (October 1976):