Arcade debit card security

How secure are the debit cards we use at arcade centres? (I mean the ones you put money into and swipe into game machines)

Is the data even encrypted?

If not, can someone purchase a device that can modify the data on such cards, to increase the money on them?

If yes, does the same key get used everytime? Can professionals take out the microchip from one of the machine's swiping outlet, and find the key (as well as the algorithm and file format)?

Or is there some kind of public key system (such as RSA), which cannot really be cracked?

Edit: Are there any such hacks that have been carried out recently?