What was it that motivated you to program those old 8-bits? For me, it wasn't the command prompt; it was graphics, sound (especially speech synthesis), and games. Based on that, some ideas about what to recommend, based on zero actual experience teaching kids to program:

0. Arduino. You can make colors and sounds that aren't locked in a box and that communicate over infrared. You can drive motors. In some cases, you can repurpose parts from existing consumer electronics. I had the privilege one weekend of helping out with a beginner programming class for artists; in about four hours they went from not knowing what a variable was to being able to program the robots they'd been given to follow a line around a racetrack. (Adults, but evidence suggests Arduino is good enough for kids too.)

1. Minetest. If they like Minecraft, Minetest is a Minecraft clone where they can write mods in Lua. This requires juggling a lot of files, and it can be difficult to figure out why existing mods are doing one thing or another, but you can add new mobs and blocks to the world that affect existing ones in a wide variety of ways. You can play it on your phone, even hosting a server, but there isn't a reasonable way to edit mods on your phone. And if you've spent a few hours playing Minetest the things in the simulated Minetest world can seem very real to you, which makes programming them more appealing.

2. Scratch or, on Squeak, EToys. A lot of kids seem to find Scratch easy to start out with but then want to switch to a textual programming language because they see it as more "grown up". And to be fair Scratch does have some real intrinsic limitations. EToys has maybe a smoother path to full Smalltalk but kids may not be impressed by full Smalltalk if they don't see adults using it.

3. Browser JS. The applicability and deployability is super high, and the barrier to entry here is pretty low if you have a desktop browser: type data:text/html,<a href="javascript:alert('hi')">x into the address bar. Graphics, sound, and multitouch APIs are available. You can easily load in images, including animated GIFs, composite them with alpha, and move them around and stretch them.

For more elaborate graphics there's both a pixel-based <canvas> API and a vector-based SVG API. You can draw SVGs with Inkscape. You can render a fractal in <canvas> in an OG Tweet, though color costs a few more bytes:

<canvas onclick="c=this.getContext('2d');function d(x,y,k){
c.fillRect(x,y,1,1);(k/=2)>1&&(d(x,y,k),d(x,y+=k,k),d(x+k,y,k))
}d(0,0,150)">

By putting your JS into a bookmarklet you can use it on pages you didn't write, including things like Fecebutt. The developer tools in the modern clones of Firebug (browser console, element inspection, CSS editing) are absolutely first class. Unfortunately a lot of this is limited to desktop browsers because vendors have deliberately crippled the browsers on hand computers; those are for consumers, not creators.

Video games are very doable in browser JS, and the situation has improved significantly in the last five, ten, and twenty years. Beginners, especially kids, would probably benefit from a game engine library here because they don't know how to combine constructs to solve problems yet. I wrote http://canonical.org/~kragen/sw/dev3/invaders one day last March, but that's four pages of code full of arcane constructs like row.push((x / barricades.dx / 2 + 12) % 16 < 8). I refactored a game engine ("qj2d") out of it and got http://canonical.org/~kragen/sw/dev3/qvaders, but I haven't tried to teach anyone else to use the game engine, and it has some stumbling blocks and boilerplate.

Chris DeLeon demonstrates coding Pong in Notepad with <canvas> in 5½ minutes in https://youtu.be/KoWqdEACyLI as a teaser for a longer course.

JSFiddle and similar services make it easy to anonymously share your work without signing up for a hosting plan.

4. Micropython, or Adafruit's fork, Circuitpython, as an alternative to the Arduino environment. Circuitpython is focused on getting beginners, especially kids, up and running with a smooth UX. What we were saying above about dropping PHP files in a directory on a server to run them? Well, with Circuitpython you drop Python files in a directory on a USB device to run them. AFAIK they don't run on the AVR that's in the traditional Arduino boards but they do run on another half-dozen types of microcontrollers, mostly ARM.

5. Proce55ing. The Arduino IDE is a fork of the Proce55ing IDE, which is optimized for making mouse-interactive graphics on the CPU, but it can also straightforwardly do sound, integrate with additional sensors and actuators, load GPU shaders, and so on. It's been demonstrated to be very accessible to adult beginners, and I think it works for kids too. You can export the results as Android apps. It normally uses its own Java-like language but there are also JS and Python versions.

6. Shadertoy. There are a lot of graphical effects that are straightforward to achieve on in a shader on the GPU but difficult or impossible to achieve on the CPU, and the Shadertoy website makes it easy to get started with that; you can edit the shader live and see the results in your browser, and save it to a URL. Also maybe check out Patricio Gonzalez Vivo's The Book of Shaders.

7. PyGame, the Python binding for SDL. You can write games in PyGame (solarwolf is in apt, and you can find others with apt-cache rdepends python-pygame) but also it's good for the kind of interactive graphical art Proce55ing is great at. You can get a blue rectangle on the screen as simply as this:

#!/usr/bin/python
from pygame import *
pantalla = display.set_mode((0, 0), FULLSCREEN)
draw.rect(pantalla, 128, (50, 100, 200, 400))
display.flip()
time.delay(2000)

And work up from there. That's https://github.com/kragen/pyconar-talk/blob/master/helloneg1..., which is one of a series of examples I wrote for a talk on this 11 years ago.

8. Godot.