Make a Tamagotchi program for the terminal that behaves like the original Tamagotchi sold as a toy in the 90s. It could start when you login and run as a daemon that would regularly interrupt your session asking to be fed or petted.
What would be really fun is if you could impose its mandatory use to many people. For instance if you were the CEO of a big company, you'd ask all your employees to have the virtual Tamagotchi installed and you could fire them if they let their Tamagotchi die.
Or maybe, make it a computer virus that would be harmless if the Tamagotchi is taken care of and deadly if the Tamagotchi is mistreated.
Are there any open source Tamagotchi emulators or is the Tamagotchi's algorithm described somewhere in a document?