Would some battons (like that: https://www.wickes.co.uk/Wickes-Redwood-PSE-Timber---44-x-44-x-2400mm/p/9000281515, or possible smaller depending of the profile of your table), fixed to the underside of the gaming top so that they’re leaving a negative image of the fixed table top? That way, once installed, the gaming top can’t slide around. That would only work well in my mind if the gaming top is a single piece.
Edit: with that idea, minimal length of the gaming is that of the table plus two thicknesses of the baton you’d use, ie. more than the 20mm you seem to have in mind. Maybe, maybe not an issue.
For the cover, I’d consider a felt with a waterproof backing, although I don’t have a specific material in mind. If you don’t add felt, I’d soften the angles of the MDF.
This is the behaviour of inet_aton, which ping uses to translate ASCII representations of IPv4 addresses to a 32 bit number. Its manpage: https://man7.org/linux/man-pages/man3/inet_aton.3.html
It recognizes the usual quad decimal notation of course, but also addresses of the form a.b.c or a.b, or in this instance, a, with is taken to be a 32bit number.
Each part can also be written in hex or octal, with the right prefix, such that 10.012.0x800a is as valid form for 10.10.128.10.
Not all software use inet _aton to translate ASCII addresses. inet_pton for instance (which understands both v4 and v6) doesn’t