Thanks to everyone (without exception) for all these good and stimulating, and newbie-friendly answers. Your answers give me the direction to go.
Apologies for having introduced the idea to join, it was a "By the way" and not the main purpose of this thread. I am really posting here to get the engine selection off the ground. But I have posted already, a week earlier than posting here, inside the recruitment section, too, for another project where I even more need people to join.
I am experienced only in graphics, and I also know, what I want (game-look). I have only beginner experience with Blender, but created 3D scenes since over 20 years with POV-Ray (unfortunately not compatible to this project). And I do cross-breeding with plants, have some gardener's experience.
Attachment: my little POV-Ray-constructed carrier spacecraft: yes, I do 3D, but not in a compatible way yet.
Programming: since 1989, but only Pascal/Delphi. But because I wrote POV-Ray scene code, I should be able to handle C in a not too uneasy way, as the general structure and ways are known to me.
I admit, there will be huge obstacles to me in developing a game, but I really want to go into it, and learn. I have so many good ideas to come, but need to be able to develop games in order to make them coming true (or through?).
I will check out Panda and Unity as engines. I was reading already about Unity, that the free version has no feature to "glue" feet on the ground (and hands on rails of stairs), hmmmm.
The game I want to develop, is made primarily only for me and maybe a small group of other persons (the chili pepper community), and a freeware project.