Instant Graphics!, or IG! for short, was an Atari accessory, (like an extension on the MAC), that monitored the serial port in the background while you were online with a normal terminal program. When the "magic" text string of G# was received, it would interpret the data immediately following as graphic commands, continuing on until hitting the ":" or return character. Everything would look like a normal online session of text messages, until a line something like this would be received...

Hello Bob, How G#S>0,7,0,0,:O,350,400,50: are you?

The little IG! snippet would draw a red circle, 50 pixels in diameter, at the XY screen coordinates of 350,400, without the embedded code becoming visible. You could draw lines, circles, arcs, boxes, fills, colors, text attributes, almost anything.

(Hmmm..sounds like souped-up HTML, don't you think? Let's see, something like this would be great to write today, eh?..

Hello Bob, how <circle="350,400" diameter="50" fillcolor="#770000"> are you?.</circle> )

But IG! was far more powerful then this. Now that the circle was drawn on the screen, you could "blit" it to memory. By rapidly pasting it back from memory to the screen in a loop, animation was possible. You would only have to add a little line like this.....

G#G>2,325,375,375,425:&>350,450,3,G,1,325,375,350,450,x,300:

The above animation is produced by a 258 byte Flash™ file. The IG! code is only 60 bytes.
Raise your hand if you think you know which one is faster and better on a slow connection. Very good!

A text file created it all. It was most excellent.

You could also define screen "hotspots", and send the text string of your choice back to the server when you clicked on it (if there had only been the URL specification then!!). If you set the text string to be a path to another IG! text file, the server would start sending it out, and you had a new graphics page. You could also control the sound chip for music in three-voice harmony, and easily transmit MIDI data in real-time too! IG! had many more commands and tricks then I will list here now, because I think you get the picture.

In 1986 a simple text file produced the worlds first Mouse-clickable, linked, musical, animated-graphic, online pages

I think it has potential.