The idea is to start off simple, with only an abstract program relying on input and output on a PC, so without any peripherals attached to the Arduino. Once I have the basics set up such as the pet's needs, I can continue to expand the Arduino with sensors, a display and perhaps wheels to replace feet. The most interesting part can only be programmed once the basics are set up: the intelligent behaviour. There are a few ideas that might be put to use, but for now I'm thinking about making the Arduino learn through genetic algorithms (GA). The interesting aspect of the animal is that it should learn how to "stay alive", which is a perfect condition to put the GA to use, to make somewhat unpredictable movements or perhaps sounds in order to live most efficiently. Ideally, I would let the pet run around with a battery and use wireless charging as "food" for the pet, so that it can sustain itself with plenty of charge left and not ruin the battery either.
I have to note that this concept is purely hypothetical so far. I'm going to purchase an Arduino soon and I'll see how far I get. I can only program in C as of now and I know nothing about the Arduino except that it is a standalone chip able to be programmed. All that's left for you, my dearest reader, is to find the perfect name for the pet's species. I've collected four names so far, as seen in the poll below, but I'm still looking for even better suggestions from you. If you've got anything in mind, just shout it out in the comments below. Any thoughts about the project are welcome too!