How do I play these games?

Depending on condition, an original Interton VC 4000 can be bought on eBay for about 100 - 200 Euros (as per 12/2021). This, however, would imply further investment into cartridges. The freeware emulator Arcadia does not blow quite such a hole in the personal budget. On its website, you can also find a large collection of box scans, manuals and ROMs for the VC 4000 as well as a dozen other Signet based machines. The emulator still comes from the Amiga era and can even still be used on that platform. The WinArcadia variant runs flawlessly under Windows.

As you can see, we don't have decent instructions here yet. If you have questions or if you want to help fill this gap, head over to the forum.