The old links are outdated.
If you accessed Eucalculia via an outdated link, you have been playing an ancient and barbaric version of the game.
The current build can be found here:
https://edefakiel.github.io/Eucalculia/Eucalculia_experimental
The old versions lack exact orthographic views of opaque solids, observer changes and reconstruction, cuts and sections of voxels, marked cube nets, masked paper folding and a few other infinite number of features. Also, the game is prettier now.
Three practical notes:
Don't miss out!
If you would like to help me refine the new prototypes, you can play with them on my GitHub: https://github.com/edefakiel
This is the one I'm currently working on integrating: https://edefakiel.github.io/Eucalculia/Eucalculia_SPA_VER_01_prototype.html
Also, follow me on LinkedIn to mog people who don't know me yet, you will be rewarded additional IQ points, but you may lose your soul: www.linkedin.com/in/alberto-flaño-lombardo-762618259