Steam is a games/software distribution platform.
3d editing: Said to be very difficult to use, and it is. There is an argument that in mastering it one gains a huge set of capabilities with one tool. I was unable to get that far.
Video editing: Requires a fair amount of setup, but ends up being reasonable to use. Selecting and moving objects is wonky because I'm used to Inkscape, but I'll get used to it.
It has a portable zip, with no install required. Yay!