What is this supposed to be? It's just a video with music and some water moving slowly around?

Garry's mod. Doesn't use a lot of resources (compared to newer games like Satisfactory), and you have an almost unlimited amount of content and things to do because of the Community Workshop.

DDG all the way

Seems quite good. Although I'm having some trouble with connecting to some instances (e.g. feddit.dk) Edit: Everything seems to work now (2023-06-17)