Research Results
So I’ve done some digging on the interactive component (the knock-off Amiibos, which need a clever name) and here’s what I’ve found.
NFC tags / reader via USB
This is the idea I like the best, since tags can be placed in cards or 2D printed models. It’s something you don’t see, like a QR code, and you don’t have to type in an alpha-numeric code. It’s a tap with a card or toy, which is a much more magical experience, which is both fun and thematically appropriate.
Tags and readers are fairly inexpensive, and the reader I’ve chosen works with Arduino. It’s possible to send information to Unity through Arduino, so I think there’s potential for this to work.
AdaFruit Arduino NFC Shield & a How-To Video for it
Connecting Arduino and Unity (one of many resources I’ve found)
QR Codes
QR codes are another possibility, but seem to be better suited for a mobile game rather than a desktop game, like I’m making currently. There are ways to use handheld scanners or webcams to scan a QR code to your desktop, but all of these feel too cumbersome. Also, if these were objects like toys or cards that I’d hope to sell, a QR code is easily replicated. They are a possible plan B.
Alpha-Numeric Codes
Probably the easiest to implement in the game, since they’re direct user input, but they’re even less magical than QR codes. Also, there’s the replication problem that could be tackled (for example, product codes for software) but verification and algorithms are not an avenue I’m excited to explore right now. This is a last, boring, resort.