A real meadow has things moving in it. Getting that into MZ normally means placing events, and once it’s twenty of them per map you quietly stop doing it.
Vivarium reads the map instead. It looks at where the water is, where the shore is, and which ground is walkable, then decides what lives there. Butterflies and bees over the meadow, dragonflies quartering the pond, fish moving under the surface, frogs on the bank that dive when your party walks up. When the screen darkens you get fireflies, moths that drift toward the party, and bats.
There are no events to place and no parallel processes. There are also no image files: all 43 species are drawn in code, wing by wing and fin by fin, as each map loads, so nothing lands in your img folder and nothing needs recolouring to match your tileset.
It leaves the sky alone on purpose. If you already run a bird plugin, Vivarium fills in everything underneath it.
Three files, and any load order works.
Disclosure: the code and the art are AI made.
$12.99 here: Vivarium — The Small Life of Every Map, Drawn at Runtime, for RPG Maker MZ by CSAF — Core Systems Asset Factory