It's nothing like Enigma: no plugboard, no sequence of rotors that can be switched out, and (as you've noted) no new alphabet on each keypress.

Enigma is not that easy to crack, even today. I wouldn't compare it to a simple substitution cipher as to laymen that sounds like it was some pretty good shit even if it wasn't as good as Enigma.

I'm pretty sure I've seen somewhere a JS implementation of an enigma cracker...

Afaik it's still quite complex to run. But JS is quite an optimised language these days, so that might not be far from the C implementation...