Walkthroughs for custom maps.

And what makes it better? You're talking about some spherical maps in a vacuum. In general, people played on fixed maps, there were even tournaments. And I myself played one game on a fixed map (I think against Dust). And the impressions weren't the most positive — pretty boring and tedious. Plus, you need to spend time studying the map, which is also boring. But when I saw the stream of the creature on a Jebus Cross — that got my interest. Even though not right away, after a year or a year and a half I had enough motivation to play Jebus Cross against an opponent myself. The fact that after two games in a row, when opponents didn't take their turns for half an hour, I got sick of online — that's not a problem with random maps, but with specific people.
Imho, for fixed maps to be interesting, they need to offer fundamentally different gameplay, which is what random maps currently provide. As different as, for example, Warcraft and Dota.

Added after 5 minutes
Actually, that's why I'm personally interested not in PvP maps, but in Co-op. So that it's not boring during an ally's turn — you can legitimately watch what's happening and give advice.