Legally it is quite clear. Taking a description of a closed source program and writing a new one is ok in most cases (unless that description is API docs - see Cisco vs Arista). Taking a look at closed source software and then implementing your own version is poison as far as OSS goes. OP implemented the first version, so that’s already a problem. They may get away is they describe what the program does to someone else and let them implement it, but OP would not be able to touch the source code
Sometimes the X is not quite at the spot. My guess is that it’s under the sand too the right on the first picture (possibly underwater).