From CATACOMB 3D Thanks — Romero, from Romero's Web you can now download the Digital Edition for free with a discount code. I really appreciate it because it lets you slide on walls, and it includes Making Catacomb 3D documentary video and PDF/ePUB article on the History of Catacomb 3D. even though it's the first version 1.00.
Before there were the 3 Big Box Editions 3 Big Box Editions: The Shallow Grave Edition (€69.95) The Stone Tomb Edition (€89.95) And the Ancient Vault Edition (€154.95). And then there was this one for €6.66.

That sounds very interesting, but unfortunately I cannot find it in the downloads section of Romero's shop. Do you have a link?

At the link: sendowl.com/s/games/computer-games/catacomb-3d-by-romero, it's available for €6.66, although the 3 Big Box Editions are officially back on sale. The discount code that got it for free is still valid, but I don't know if I can publish it or if it's private.

Thank you very much for the link!
I just bought the game via that link. I personally don't mind spending €6.66 on a legal copy of Catacomb 3D v1.00. For me this opens up an opportunity to add support for the Big Box Editions to CatacombGL, without the need to actually buy a Big Box.