One thing I realized about Doom (1993 video game) is that -- sure, it's got scary monsters and cool weapons, but what really makes the game awesome is how these elements interact with each other. For example, an Imp has just enough health to be taken down with one shotgun blast, so in the early stages of the game, getting anything stronger than the pistol will be a priority when you encounter a pack of Imps. And a Cacodemon is very dangerous, but it has a high chance to stun, so you can pretty safely kill it by stun-locking it with a rapid-fire weapon like the chaingun. The way the monsters behave, together with the terrain, allowed the developers to combine just a few elements to create a huge variety of combat situations that pretty much required the use of every single weapon, and a variety of skills and strategies from the player.

And, not only did this make Doom a more exciting game to play, it opened up an enormous possibility space for user-generated content that a dedicated fan base is still exploring nearly three decades later.

Lisp is like that. It's not just that it has a REPL, or macros, or homoiconicity, a fast compiler, incremental development, or that the evaluator is itself built into the runtime -- it's that it has all those things, they compose nicely, and they interact in such a way that it opens up a tremendously huge possibility space to even a single programmer that other languages do not. Could you countenance writing an expert system in Java? It's possible, but it would be tedious work.

And Lisp's dedicated fans are still exploring that space today, six decades later.