You're thinking of the right game. You had a pet that was pretty much a massive bipedal animal monster that you could train. Depending on what you do with them, when you reward them with food and petting and when you punish them by slapping them, they'd change their behaviour. You could teach them to either farm food off of fields or eat villagers when they were hungry, whatever you wanted. It was a really fun feature, at least for six year old me.