[PvK]

Yes, Arcologies can only be built from the ground up, because they are not just mega-cities piled on old cities (those are Megalopoli). An Arcology is a completely different kind of thing, with its own eco-system worked into an artificial vertical environment.

Aub, I think I may have an observation that will help put your mind at ease about the upgrades of facilities. When I worked out the numbers for the cultural and (mega)complex facilities, I did consider that the upgrade mechanic was kinda lame, and that it would be annoying if players had to micro-manage their use of upgrades in order to stay competitive with opponents. For this reason and for other design reasons, I chose numbers for costs and output designed so that it actually isn't an advantage to try to abuse the upgrade system, because it's actually better, in almost every case, to build a new facility, as opposed to upgrading to a larger Version of the same type. The only advantages of upgrading (and of choosing large facilities) are in terms of concentration on single planets, which helps in terms of compact defense, and ability to combine bonus effects. In general though, you get more, and often sooner, by just building more smaller facilities, even if you're only upgrading one at a time.

So, at least if you're just trying to maximize your empire's total production, again, you can just follow the simple "fill up on simple facilities" system so familiar from SE4.

There are several advantages to the larger facilities, and in some cases, to upgrading, but in general it's pretty safe to assume that just building new stuff is actually more efficient, as long as you have slots to fill.

On the suggestion to tweak the upgrade costs, I'd love to have such options, but that's another thing the current SE4 doesn't let us mod.

Ok, so it does stink that SE4 only gives limited upgrade options. But as oleg and others mentioned, I added the upgrades at the request of players who enjoy it, and I think it's nice to at least have some ability to upgrade, at least as long as it's balanced so that there is no trick that makes it more efficient to upgrade than to build normally. (For instance, this is why I made Communities not upgrade to cities, because it would be a shortcut in terms of costs, which I can't mod.)

PvK