Does anyone here know anything about making a Tamagotchi-esque virtual pet toy?
You can start by making one entirely in software on your PC. Getting a feel for the software requirements before designing any hardware is a good idea. Besides the software, the hardware can be as simple as a microcontroller, LCD module, piezo buzzer and a few buttons. This could be implemented quite easily as an Arduino shield. There may even be an LCD shield with buttons already made you can use.