I suck at thinking of amazing game design ideas so I'm gonna ask for sugesstions. What do you like to see on a pet simulator. The main inspiration is Monster Rancher 2 for the PS.
 
Features I've already planned:
Tournaments
Growing up differently depending on how you raise it.

Thank you for those suggestions! 
 

hard mode where it's very unlikely that your pet won't end up a lazy, overweight fuck or suicidal or both

This is a good idea. I don't exactly like havin to have different difficultes so I guess the difficulty of raising the pet depend on its "race" or characteristics. And f course, since it's harder the rewards of raising it successfully would be better.

procedural pet design. the name that you give it generates a random pet, wch can be changed and improved indirectly by how you care for it.

I like this as well but it'd be real hard to implement from a coding perspective.

the ability to feed older pets to new ones, thus passing along the accrued stats of a former generation.

This is good especially since I plan to make pets have a limit on age, so it'd be a choice (ethical?) to either bury it or feed to a new pet.

tamagotchi like interface.

Not familiar with it but right now I have a working template on the interface which is basically a front view of the "room" where the "pet" roams and buttons where you can feed, clean, play, or let it sleep.
After I get the basics of the interface down, I'd add being ableto decorate the place and "dragndrop"ing food, toys, etc..

an ultimate goal.

I will make a plot for it
 
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Early prototype (the graphics are all placeholder but I plan on keeping the cartoony theme on the final product)

Thanks. Yea, I also have the weather idea but that would wait as a later feature.
 

also, if you're going for a more family friendly vibe, feeding your pet to another may be a bit too grim. something like a pet death ritual, where it passes down it's knowledge then passes away, or something?

 
Nah I'm not going for family friendly, just the graphics so the pet eating is ok.

Maybe you should use object oriented programming so you can have multiple pets and use a similar menu system to what you'd get with characters on The Sims? So a radial tree menu structure?
 
Having drawn graphics is the way to go as indie games are saturated with 8-bit style stuff right now.
 
Perhaps minimising the amount of GUI on screen at any one time unless you hover over particular things, this could perhaps be a feature of said menu which appears in the context of the pet under focus.
 
Disease probability and prevention could be cool. So you could *find* text snippets throughout the game that test the players memory with regard to what the dos and don'ts are for a specific subclass of pet type. E.g. if you let their food go off flies could come along and if they are present for more than X amount of time there is an exponential decay of 1-the probability of it getting a disease and depending on how well you've been nourishing your pet it could determine whether it could fight it off or not.
 
You could have ridiculous diseases also, such as bloaty head or slack tongue (borrowing a bit from Theme Hospital there, I admit but you get the picture).
 
You could make time advance through ages and make it so you can augment your pets when they get old and it's the future, making them invulnerable to traditional diseases but vulnerable to hacking. You could instantiate minigames to *fight off* or *identify the hacker nearby* so you can shut it/he/she down.
 
I'm just spewing ideas, feel free to ignore me. It's looking good so far!

Maybe you should use object oriented programming so you can have multiple pets and use a similar menu system to what you'd get with characters on The Sims? So a radial tree menu structure?

The radial menu is a good idea I would have to implement that. It actually reminds me of a menu system from the GBA Mana game (Swords of Mana?), it's also radial but you'd see icons as menu options instead of text(as in The Sims).
Actually I'm using a game making software for this (Engine001) and there is support for Templates, so I guess in a way it's OOP since I could make many pets from the same class and templates could inherit from other tremplates as well so I' have no problem designing and exanding on different races, etc..
 

Having drawn graphics is the way to go as indie games are saturated with 8-bit style stuff right now.

I completely agree.
 

Perhaps minimising the amount of GUI on screen at any one time unless you hover over particular things, this could perhaps be a feature of said menu which appears in the context of the pet under focus

Yea, I need a bit of cleaning up but all of those graphic/format are just placeholder just to test out the core features.
 

Disease probability and prevention could be cool. So you could *find* text snippets throughout the game that test the players memory with regard to what the dos and don'ts are for a specific subclass of pet type. E.g. if you let their food go off flies could come along and if they are present for more than X amount of time there is an exponential decay of 1-the probability of it getting a disease and depending on how well you've been nourishing your pet it could determine whether it could fight it off or not.

I could imagine this working but it could get very complicated easily.
 

You could have ridiculous diseases also, such as bloaty head or slack tongue (borrowing a bit from Theme Hospital there, I admit but you get the picture).

Noted. Those are pretty funny diseases. ​)
 

You could make time advance through ages and make it so you can augment your pets when they get old and it's the future, making them invulnerable to traditional diseases but vulnerable to hacking. You could instantiate minigames to *fight off* or *identify the hacker nearby* so you can shut it/he/she down.

This is a bit feature creeping but I appreciate the suggesstion
 
--UPDATE to Development
I planned on finishing the first section of core features today but I run into a couple of problems which slowed me down. Primarily it was caused by non-familiarity with the software but now I'm getting the hang of it. Inventory system is working and I believe I'm doing the right building blocks of the basic engine so after this, adding content and polishing stuff up should go smoothly.
Now I'll have to figure out AI and the Pet Behavior. This is a challenge since I need to keep in mind and build upon the idea of how the system will expand later on (with diff species, attitude, statuses, etc..)

The variable result of growth is a really excellent idea, thank you that. I've thought of something similar but I'd still think about it. If I implement it, it would only be either 2-3 growth outcome since the monsters already have their specific specie.
I was actually trying to follow the Monster Rancher route and have breeding (in MR it is actually combining) to produce different kind of monsters with having slight variationson appearance and of course stats. And adding another dimension like different version of growth would of course exponentially increase the complexity of the model. 
Anyway for the first version I'm limiting myself to 12 base types of pet. Haven't thought o the combinations yet but hopefully it won't go to the hundreds.
 
BTW, I'm starting to teach myself some Vector illustration and it's really fun, I'm planning the artstyle to go that direction.

About the pet shows, yea I think I'll put that one in. The first game that comes to mind is the contests in Pokemon Sapphire/Ruby/Emerald and I might do something the same which will tie in the moves/stats that are used in the tournament into a completely different kind of competition.
Is cruft a game?