The proximity sensing used on the map is self-capacitance sensing, which simply means each area on the map will have a dedicated touchpad whose proximity will be detected individually.

The Capacitive Proximity Controller

I originally planned to use an Arduino Zero board to control the proximity sensing on the map, I chose the zero because it features the ATSAMD21G18 chip, a microcontroller from Microchip that has a capacitive sensing module built-in, but I realized I had a different chip, the ATSAMD21J17 which I bought for a different project, this chip is part of the ATSAMD21 family of microcontrollers, so it also features a capacitive sensing module, with the added advantage of having more pins and hence more capacitive touch channels. I designed a very basic development board using this chip,

Board files - https://github.com/ahmsville/ATSAMD21J17-DEV-BOARD

Pads

the areas on a map usually have different shapes, and sizes, I needed to figure out to put a capacitive touchpad behind each cell on the map, for this I decided to design two custom PCBs, the board is just a simple square board with a circular pad in the center, I made the board in two sizes, 50x50mm and 20x20mm, the larger pad will go behind the larger area on the map, while the small areas will have the small pad.