Late For The Sky -V- Hasbro Monopoly

Firstly, thank you for allowing me to become a member here. I have been an avid reader for a while now and decided to join for one reason to post this question to the members and secondly to gain some knowledge from the experienced designers in here. I have two game concepts one which I believe to be unique which I will put out there for opinions soon, the other a Monopoly derivative and on that one I'd like some feedback from you guys.

My "Monopoly" derivative is a travel based board game built around a world famous tourist destination (which I hope to be marketing to support a charity in this location). It will therefore not be in global demand but rather appeal to this destinations native population and the millions of tourists that come to this destination every year. I have great marketing contacts here and see no problems marketing the game to my target audience.

I contacted Hasbro to see if they were interested, they responded by saying that they would sell me produced licensed games, but the MOQ's and price (was like a telephone number), so I decided to look around for alternatives.

My research found a board game called "PARIS-OPOLY" and that landed me at "LATE FOR THE SKY", publishers of hundreds of "-OPOLY" knock offs (including one for just about every State/Town in the USA). I contacted them with my concept (excluding the destination name I am targeting) and they were keen on the idea and gave me a price list for 250 (their MOQ), 500, 1000, up to 10,000 units. MOQ's are more realistic than Hasbro and their unit pricing is around 50% cheaper than Hasbro's but still up there in terms of making any sort of profit (I want to try to keep the RRP to under $40 if I can).

My next question to them was,"Are you licensed by Hasbro ?, if not how do you get around copyright/patent rules etc... I don't want to go to any expense and find my stock seized or that I am being sued by a corporation."

Their response, "We do not have a licence agreement with Hasbro. In the early 80's the concept of the game play became public domain. So anyone could make a "property trading" styled game if one did not infringe on the original design of "Monopoly". Please look through our pricing information and contact me with any questions you might have."

I have looked on their website and taken just one of the hundreds of "OPOLY" games they have published and for the love of me I can't see changes that would set it apart from the original Monopoly. Are they right? can someone show me the areas which they have changed enough to avoid litigation from Hansbro. They obviously have got Hansbro cornered because as I say they have produced hundreds of Monopoly knock offs over the past 15 or more years. Can someone enlighten me on what it is they have changed to elude Hasbro, all I can see is the "Jail" square changed to "Traffic Jam" and renaming of Community Chest and Chance cards and renaming of streets and colored place bars replaced with banner/flags.

https://www.lateforthesky.com/board-games/city-games/paris-opoly/

Can the experts show me any other differences they see that makes this not a knock off of Monopoly? How do Late For The Sky Do It?

Sorry to be so long winded on my first post.