I haven't had a chance to sit down with this simulator, but having used both Decker and HyperCard before, Decker has a much steeper learning curve for a beginner.
The programming language in Decker is called Lil and it's a cross between APL (how it works on a vector) and a procedural language. Once you get the hang of it, it can be very powerful. But as someone that used APL (and K) and has experience with multiple other language, it was a tough grind. It helps to look at the code behind the tutorial, there are lots of great examples there.
The author (who is super responsive to questions) is clear that they liked the look of the dithered black and white from the early Mac era. So it's more of a homage to that than a hypercard.
It's fun to play with once you get the basics down. Simple drill and practice is easy to build (ie States and Capitals). I'm sketching out how to do the Ham Radio technician license test practice in it. I'd like to be able to do the math for some of the examples on the screen.
