I'm working on a team right now for a pet game, like Chaos in Sonic, Nintendogs, Tamagotchi, etc. You have various stat bars that you should be keeping filled (not sure of the consequences for not doing this yet - which makes me cautious) and you can level up your character by playing with them, which gives you access to more items to customize with.

So you start the game and there's your pet with a few furniture items you can click on. You can click each furniture item to access a different menu - minigames, clothes, food, medicine.

The goal, I believe, is to level up the character by playing with them so that you can customize your character more, and that's about it.

How do I convey this objective or basic concept without tutorials? Mario, Megaman X, and any direct manipulation game seems to have no trouble with this, but I don't know of any pet games or second/third person manipulation games that don't use a tutorial. Any tips?

Tutorials almost always blow. They're either confusing or insulting. I paid good money for GTA V, and the fourth time it stopped the action to "teach" me something I learned ten years and 300 hours of play ago, it got turned off forever.

So I agree that you're better off without them, in the hand-holding, "Our players are drooling imbeciles," sense.

Will you have cues from the character that indicate when a need isn't being met? Maybe you could have the critter look bored and have the "play" meter blink or glow to indicate that the behavior has an intelligible cause. Then, let the player right-click on the meter and get a contextual menu explaining the factors that influence it.

There's a little game on Steam called Redshirt. It's concerned primarily with the management of status bars, and the interface allows you to quickly learn what actions will influence a given meter. The challenge lies in finding choices that bring about the most desirable combination of results, so you're balancing different actions in order to tune and tweak the system. If your game could provide the player with information about what choices bring about what results, then they can spend less time on trial and error and more time on orchestrating an outcome. Poking a thing to see what happens is research; poking a thing to make it something else is art.

You might also consider Tool Tips which can be checked off by the player when no longer needed.

If navigation of the game largely revolves around clicking on a piece of furniture then working through a menu associated with it, you'll want to make sure that the furniture pieces stand out from the background in some way. They could have an outline. You could put a small "New!" icon over them when there is a new activity or customization option. In your type of game, smart visual design is everything. You should also make a point to use items that can be easily associated with the menu beneath it. For each of the ones you mentioned (minigames, clothes, food, medicine) you can use (a playset, a closet, a fridge, a medicine cabinet) and so on.