There are several types of video games but the most used by what I have seen, to generate alternative income are the MMORPG, MOBA:
Moba:
They are multiplayer video games that consist of a combat arena, also known as real-time action strategy games, games that are selected, electronic sports in their majority, coast that the teams learn from each other, with each player controlling a single characters, have ranking systems for ranges, levels that are acquired in the account, different missions with fur prizes and others for players
There is a system called Elo-boost is used by many gamers with experience in the game in which they provide a service to less experienced players and the accounts to raise their level accounts, acquire prizes and raise high ranks accounts accounts in the systems qualifiers
MMORPG:
This type of games are very appreciated by the communities of players that allow the connection of miles of people in a virtual world on the Internet simultaneously, in this type of games, each character implements a role, a class, a different race with choice to the user's taste Within these games different types of activities are carried out individually or entering brotherhoods or guilds, an ecosystem of commerce is created with purchases of items, armed weapons, capes, costumes ... among others.
In order to have good exchanges and generate income, my recommendation is that there are a number of accounts in some virtual wallets such as PayPal or Neteller since these are the most common platforms where you can receive your money, Another option is the use of Cryptocurrencies and thus be able to make item exchanges for the currency of your preference.