A modern definition of ROBLOXia is basically the whole world ROBLOX takes in, as used in the popular game, "Heroes of Robloxia", and officially in [Roblox Toys FAQ].
As ROBLOX evolved, ROBLOXia did too. It all started with a simple game, "Welcome to The Town of Robloxia" created by 1dev2. Fortunately, the creator refrained from copylocking the game. Many users have copied the game and added updates to bring back the memories but in the modern style. Updates have been added such as; more cars, more buildings, more jobs, better house, longer roads etc. Majority of these copied games are called, "Get a Job, Buy a House, Be Rich!", "Adopt and Raise a Cute Baby". However, all these games contain the same map.
Technically, there's no objective in the game since it's roleplay. ROBLOXians are free to drive around and explore. There are no actual jobs in the game. A "Choose A Job" option is displayed when entering a game. Clicking a job will just spawn you to the job related building. Houses can be bought for FREE and have options (when bought) to lock house, lock garage etc. Money is earned automatically (10$ for every certain period of time) and it can be used to buy grocery at the "ROBLOX MART" which located towards the eastern side of the map, beside the residential neighborhood and south of the restaurant.
This game may seem neat, however, it's heavily criticized for promoting Online Dating. Today, when a player enters a server, majority of the messages in the chat box are consist of players asking for relationships and kids to role play with. This criticism didn't start at 1dev2's original place, but rather in today's updated versions because of their catchy names such as, "Adopt and Raise a Cute Baby", "Get a Family".