The concept of virtual currency is present in almost all kinds of games. Each game has its own kind of in game currency. In fact, there are even some platforms that has its own currency like the PlayStation Network. You can think of it as some kind of virtual currency that can be used to buy and trade goods just like Bitcoin. This is something that can earn by playing the game and achieving some goals and or buying the currency using real money. Either way, you will get what you want using these methods.

Roblox
Robux is basically the in game currency for Roblox. This is a game that allows the player to play different games within the platform, as well as create environments and items using basic blocks. There are some items that can only be bought using the in game currency which is an additional revenue for the developers, and another challenge for the players. This is actually something important since it gives the game some kind of hindrance that challenges the players. In this platform, you can buy almost anything with the money like space, building blocks, clothes, designs and even avatar accessories.

Hacks
Since in game currency is viewed as a hindrance more than a challenge, there are some developers who created a way to get free money without even doing anything in the game. These are cheat engines and they are not only available for Roblox. In fact, this concept is as old as gaming itself. There are really old games that still has their own cheat engines. These engines can do different things like improve stats for the avatar and give free in game money. Instead of being viewed as a bad thing, it is actually being celebrated by many players since it gives them a lot of benefits.