Where do i start making my first 3d games without completely pre-made stuffs and scripts?

I started making games with gamemaker when i was 13 years old, now i can make really nice games with that, i also have some experience in runescape private servers and i know the basics of c++. Now i want to try making my own simple 3d (multiplayer)games and learning it trough playing around with it. starting with a kind of maze game with small objects u have to collect and tiles u better shouldn't step on, and ending after a few moths with a own made 3d landscape with clipped walls and doors i can open and walk around in a simple multiplayergame. Like how runescape started ten years ago as a small game made by only one guy and made better and better every few months. But i have no idea where i have to start, what free 3d landscape and object designer i could use, how i can make simple animations like a humans legs that move if he steps or runs, i don't know what free game engine i could use to make my own games, i am NOT talking about pre-made stuff that you can change a little like FPS-creator. I tried unreal engine but that is not really what i was looking for. I also tried dark basic but that is crap. Plz don't start flaming, i know that i can't make the next call of duty and that it will take years to be really good and that companys have many people working on only one game,.....!