Hi Dex, I've played all sorts of games over the years. I really like d&d type games but I don't play online as I hate pvp. I've lost count of the times I've asked devs for an opt out. I just don't get the mentality of killing another players character, and I get sick of dealing with power hungry psycho bullies when all I want to do is finish a quest. I gave up looking for an RPG with no PvP.
I do like pet based games, currently I play a horse racing sim and a horse ranching/exploration game.
One of the best games I ever played was a dog agility game for android. It was fast and furious fun, and you controlled the dog by tilting your tablet. I think it was probably someones college project, it wasn't around for very long.
What would my ideal game look like? An open world with muliple player races where you can build towns/farms plenty of crafting opportunities, livestock raising, quests/puzzles and a few dungeons because some days you just want to kill something.
A couple of ideas I've seen posted online....
A cattle ranching game.
A sheepdog trials game.
Also, kudos to you for wanting to make a free game, that's a rarity in this day and age.