After playing a bit with the first version of the board I decided to release another version with a few major fixes. 

Most notably, a buzzer and battery connector are added. Sound is an important part of the gameplay, as your pet uses voice much more often, than you would hope. Buzzer was present on the first version of the board, but the schematic and pin I picked was causing permanent low volume noize in the Buzzer, so I never advertised it as a feature.

As for the battery connector, it was also planned in the first revision, but the off-the-shelf module I selected was very picky about the battery voltage, particularly didn't want to start reliably with Ni-MH rechargeable batteries, due to their natural low voltage.

For revision B I did my own schematics on the board. It still has some place for improvement, but essentially it works. I'm planning to work a little on the firmware to reduce current consumption and make battery life longer, but right away it should work for a few days on the pair of AAA batteries.