Walkthroughs for custom maps.

Not least of all, after playing this map, I started to enjoy "underpowered" map types, where the player is significantly limited in some way.

I've always preferred such maps. Especially the limitation on artifacts. I simply hate maps with their huge number of artifacts, which force the player to sort through them, trade them, or sell them, etc.
And having tens of thousands of units in each slot in your army somehow diminishes the sense of danger. And tactically, IMHO, battles with such an army are less diverse.