Not only would it be a herculean task to update decades of work, but many of the companies involved also consider the inner workings of modems to be trade secrets.
This is the actual problem. If the modem code was open source, finding and fixing vulnerabilities like this would be far easier.
I have probably clocked hundreds of hours into Gauguin. It's a sudoku-esque puzzle game about filling numbers in a grid. It keeps my quick math sharp.
Also, it might be a bit on the intense side of casual, but Balatro is probably the best mobile game ever made.