Why not just use another "arduino" as the pseudo credit card.The ESP8266 modules (for example the Wemos D1) have Wifi as standard....R
@Whandall: Which one is more accessible to use in your opinion: NFC or RFID?
I guess I 3D print some kind terminal (arduino inside), to simplify the paying process.
there will be 3 to 5 players exchanging money between eachother and the bank.
Is there any reason to store any information on those "credit cards" other than the card ID itself?That's the description we really have. Do those players have to be able to exchange peer to peer, or only through a reader? In the first case you need "smart" cards that can store info, communicate with each other, have batteries, etc. In the second case a passive RFID is enough, as all the accounting is done in the reader itself.