Hii, I'm unikilling (in roblox)
I was thinking about add and wall piano(?), or any function that makes the player can play piano by themselves, with the keyboard or the finger in case of phones or tablet. A function that change the playing mode to manual instead of automatic or predetermined, maybe you can use as an idea the pianos of visual piano in roblox.
I was thinking too in adding small pets, as an example, acuariums with fishes, aquatic turles or land tortoises, reptiles, hamsters, guinea pigs, hedgehogs, etc. Not a dog or a cat because i know that it's difficult to program. With the pets in case of take the idea of small pets, maybe you can add a pets store with terrariums, meal, and substrate.
That's all, and to be clear, the first idea is the one most realistic and the most achievable in the short term.
Sincerely, unikilling.