fly through software wanted

This forum is mostly used by the 3D designers/sellers of CGtrader, probably 98% of them use windows and know very little about Linux or its apps.

Unreal Engine is indeed top-notch, Unity is another one (close competitor to Unreal Engine). I believe both of them can run on Linux, don't know how Debian will handle, its Linux at its core right?

Note; Unreal and Unity are geared towards real-time rendering and game programming/scripting, if its just rendering you need then Blender can also do the trick (with native real-time Eevee renderer) and you get full 3D modeling + procedural node based modeling and animation in one app.

Lots of apps out there but apps like Unreal engine, Unity and Blender are very popular so lots of tutorial makers for it and big community to ask question to (very important when getting onto this type of tings).

Unreal Engine Version 4
It is free. Tons of learning tutorials available. But, it does not import files in *.stl format.
To get stl files into Unreal Engine, you first need to download a free copy of Blender. Blender (a 3d model-building software) can import files in *.stl format.
Inside Blender, after importing an *.stl file, export it again into *.fbx file format. It is not difficult to learn a little bit of Blender - just enough to be able to import and export files.
Unreal Engine will read a file in *.fbx format.

Alternatively, locate a person who is willing to convert files from *.stl format into *.fbx format for you. I can do this, but do not have to time to make many file conversions. Could convert maybe five or ten for you.

I did not get email alert that there was a reply to my post. It is good that I checked the forum.

To Forester. Unreal Engine 5, was launched in 5 April 2022. Blender is difficult for me to learn. I have blender and have used it. My old bpy script and many scripts on internet stoped working when blender was updated. But you use GUI instead of bpy script? I would like bpy script that does what I want and works on current blender engine. So far, it looks like my best bet is for me to try writing bpy code for current blender. Thank you for your offer but convertng file formats is a minor issue, my present effort is to find an engine.

To iterateCGI Yes, Debian is Linux at its core. I researched Unreal Engine and unity. It seems they will be difficult to get working on my system. My repository has some other engines to try.

Here is another idea. If there is an online version, then I would not worry about installation. Or someone else with the engine can shoot the video. Or I could buy a windows system if I had money.