Help finding a game to play?

I need some help finding a game that has no real ending. Not an actual ending an not a point where no effort is nneeded anymore, perhaps a game where you can build bases agains enemies and there's no such thing as a "safe base"

examples of games that get boring: minecraft make an iron door and the challange is gone

farming simulator, at one point your economy is unstoppable

kerbal space program, at some point you get bored of repeating the same things

so some game tips would be awesome.

Runescape 2007, leauge of legends

The witcher 3, diablo 3