oh and one more thing which pictures in the gallery involve transformation?
As of this moment:
Flower blossom
Beelina (wasp girl)
Doggo boy
Living shard (floating crystals)
Lingua wyvern
Bewitched Commander (werewolf)
Clematis the Arrogant Witch (turned into a dildo, no instant loss or permatransform; gender bender, femdom, vore)
Mannequin (this is probably loosely transformation, where you technically get turned into one, but by soul swapping)
Happy Pudding (unsure here, really, but I'll count it)
Obscure pain thing (paintings on the wall)
Mothrinaa (moth girl)
Medusa (petrification)
Drone tester (has 3 different transformations into enemy monster girls, but none are instant defeats)
Hunter of Tyrants (the not-Krystal boss; furry gender bender, sex scene. not an instant defeat)
I think that's it so far. I know some are planned to have more. For the mushroom girl after she digests Maya, she would turn into a mushroom girl from the expelled cum. And if you read the info for the Koboling, it's hinted that there could be a game over where they turn her into a "koboling queen". Unsure about any other enemies that don't have game over scenes.