To not be a copyright violation, it should be far enough to look like an accident. Posting a confession about knowing the game's similarity here would be used as evidence after a quick web search. I would advice against it, but either way, an original game will be more succesful at standing out.
For a part of a game to be patentable and receive a more far reaching protection than copyright, it has to solve a real-life problem as a thing or method. The inventor must also have applied for the patent before showing it to the public. LEGO failed to claim copyright violation in a case where the defender making LEGO compatible products ascended the product from artwork into invention, for which the producer had not applied for any patent. If the physical analogy for game rules is a boardgame, then it's artistic work and no patent would be approved. Just like a soup recipe that comes and goes by accident all the time depending on what's left in the fridge. If the game however comprises an advanced method for video compression, the patent of that technique would refer to a dedicated machine for making the video take less space.
I'm not a lawyer, but I have written a patent application as a part of my old job. Everything is a gray area when dealing with firmware for mobile phones because it's often competing against dedicated hardware solutions running the same methods. The same applies to computer games that are essentially simplified simulations of the real world. Both worlds have trolls.
Laws are fuzzy and constantly changing, so don't ever think that you're safe from a single detail. Sweden even has an unused law against extremely morally wrong actions, which could counter any loophole being exploited.