Both Mindustry and Freeciv made it to the frontpage of HN today so I feel it's necessary to share the OS Game Clones site in case people haven't yet looked through it:
We all stand on the shoulders of giants, almost nothing is really new, we've all seen it somewhere before. Everything is inspired by, iterated on, or grown from something else.
If clones weren't OK, we'd only have one company owning each genre of game. That'd be no fun at all.
Why wouldn't it be acceptable? As long as you don't steal assets you should be free to write any computer program you want.
> Therefore, the systems or processes that make up the core of a game—generally referred to as the “game mechanics”—are not subject to copyright, even though the written rules, game board, card artwork, and other elements—often referred to as the “theme” of the game—may be. Game mechanics can be as simple as “roll dice and move a token along a track,” or far more complex. Regardless of the complexity or originality of a given game’s systems and processes, its game mechanics will likely not be protected by copyright.
[0] https://www.americanbar.org/groups/intellectual_property_law...
The link between Veloreon and Cube World, for example, seems really shaky to me. I definitely wouldn't call it a "clone" but it definitely fills a niche Cube World left