Aquaman

I also like Space Ram and Millypede

I bought it in 1983 within the Netherlands. No signs of any replacement power plug or other strange things which would suggest it is of UK origin.

In the Netherlands it was also the Mattel Aquarius

Any change to see at least some screen shots from the running game Diamond Mine

After purchasing the physical tape, Roy Templeman was kind enough to give me a password to download the digital ROM.

And if not, with every tape sale, you will get the digital ROM version of the game too😜

Within Vaq72a / submap tools there is a program called CaqtoWAV this should do the trick, although I never personally tried it.

Could this be the Fred Horvat we are looking for? https://twitter.com/fmhcom Maybe someone has a twitter account to reach and ask him?

At least all the other games, on this order list from Add-on Electronics, have surfaced. This could indicate that a release was not far off.

It's a pity there is so little info on the mentioned games

You are right I didn't notice these right away.

There is also a mentioning of Dungeon run

Diamond Mine is an Aquarius gem that's for sure!

I think it even reads Spectrum at the top corner, but of course I hope not!

I think this is the same one for the ZX spectrum https://www.mobygames.com/game/zx-spectrum/biggles/cover-art/gameCoverId,121179/