Ultimate Edition's core feature is the overworld, and none of its architecture works without it. So the first thing to do when planning a UE game is to set up at least an outline of the overworld. And that's where Cult Engine Zero comes in.
CEZ is basically this site: https://interactive-img.com
You go there, make an account, and can turn any image into an interactive one with a few clicks, zero programming knowledge needed. In our case, we want to turn a map into an interactive map, i.e. an overworld.
This is the service I used to publish the first version of the overworld before there was a Battlegrounds at all. It's what I used to attract players to my project, and I initially made a Dark Sun overworld, just a basic one with a couple of starting adventures on it. Then I made one for each major D&D world, and put a basic HTML site together with all of the maps on it (the game back then was called "D&D Battlegrounds"). At some point though I switched to Pathfinder when I realized it is ideally suited to be the starting world, and ended up making what still remains the greatest overworld ever: https://interactive-img.com/view?id=18493
(Note that this link won't be functioning forever, I'll retire it once I move all the content to the latest version of the overworld, but you'll always have the image here to inspire you.)
You can put this together in an hour or less after you made your account (though with fewer points of interest than mine; if you want to add all the Pathfinder APs like I did it will take you a while), and you can then show it to prospective players to attract them with its gloriousness. This is the exact map we used to have our teams pick their first campaigns back in late-2020, and in fact we still use this map to this day (but won't be using it anymore very soon). So for several years this map was perfectly functional for us. Note however that with the introduction of the adventure-strategy layer aka Master of Heroes in Battlegrounds Alpha 2.0, this engine won't be able to handle it, so it'll be retired. But Cult Engine Zero will still be the fastest and simplest way to throw up at least a prototype of your overworld, and show it to your players to pick their starting adventures. Then you can dig into more advanced Cult Engines after you've run the skeleton/prototype game for a while, and you find the time.
It costs something like $5 (or I think they raised it to $6 now) per month to unlock all the features, but it's more than worth it. Some of the best money I ever spent in gaming, and would have gladly spent much more.
This is what it looks like when you're utilizing all the engine's features:
Note that some of the rules have changed, and even the placement of a few of the dots because some of them represent upcoming content not yet published by Paizo at the time, so I couldn't know the exact starting locations, so I put them on the overworld in the general area of where I suspected they would be. But you get the idea of how the thing works, and there is also a little advanced functionality such as blinking dots and YouTube embeds. The entire map itself can be embedded in your site, if you have one. If you don't, it's not a deal-breaker, you just give your players the link to the engine's site.
It is possible to link multiple maps together in order to represent entire regions and adventure locations, but it must be hacked together by including links in the pop-ups to further maps. It's not elegant at all and that's why I never tried it, but it can be done for GMs who are reluctant to move to higher Cult Engine versions. The problem with the dots is that you can't place them with any degree of precision, the tool doesn't allow for it, so they work in the most zoomed-out map to represent entire adventures or campaigns, but if you want very zoomed-in views with details such as the exact party location for example, you can't really do that here. You need to start thinking about moving to Cult Engine 1, or even better to Cult Engine 1.5, which is where my Battlegrounds is at right now, but perhaps not for long ;)
