Forms of Business Models
Selling a game via retail means selling an actual physical copy of the game that you can buy straight from the shelves. It usually involves shipping many copies of your game to various stores. This is not limited to physical shelves, this also includes websites such as Amazon, where they can ship a physical game copy to your door. Retail allows for the games to be sold and re-sold as used, buying a game used is usually cheaper, but your copy of the game will possibly not be in a great condition.
Digital Distribution is where people will download the game and can own it out having to have a disc or physical copy. Many companies offer digital distribution software, one of the biggest and more noticeable is steam, which offers a large list of downloadable versions of games for the PC platform.
You can easily apply to put your own game on to steam or other digital stores, it will just require that you offer them some of your revenue that you make. Taking the digital route is definitely cheaper as you do not have to spend the money in-order to make physical versions of the game.
In some games you may recognize some brands advertised or shown throughout the game, in order to gain some extra money, game developers sometimes ask other companies if they would like to have some advertisement within their game like a brand of some kind. The other companies pay the the developer to have a form of advertisement in the game. This can take multiple forms, sometimes it can take place as a physical advertisement in-game such as a billboard, sometimes a character can use that brand, for example if they take a drink of something, the drink could be branded as a real life drinks brand.
This is commonly found on internet browsers, if you are playing a game in browser, for example a flash game, you will most likely notice that around the borders of the game are advertisements for products, sometimes those advertisements can be of games. Around-Game advertising is not very respected as scammers use it to their advantage.
Some companies has advertised their brands by creating entire games. one of the more notable for doing this is Burger King, they created an Xbox 360 game based upon playing as the Burger King where you go around feeding burgers to people who are feeling hungry.
Game demos, also know as 'try before you buy' is when a game developer releases a free (usually) version of their game. The demo is very limited and usually contains at least one level from the full game. Sometimes developers go the extra mile, and create a unique experience for the demo that won't appear in the final game.
P.T. was the demo to the new (now cancelled) Silent Hills, it offered a level that was not going to be a part of the final game, they tried to compact as much as the game's experience into one short game allowing people to try it out. People have respect for demos as when buying a game, you don't really know what you are getting yourself into before hand as you've never played it before most likely. Demos allow for people to play the game before hand and no what they are getting themselves into before making a purchase.
This method borrows from TV where it releases the next part of the game over a series of 'episodes.' You either will have to buy the episodes separately as they come available or you can buy them in one go and receive them instantly as they come out. When performed correctly this method works really well.
One developer in particular has become quite the gaming icon with its fantastic story based episodic games, Telltale Games. It has multiple games series based upon TV shows and other games series, such as The Walking Dead, Game of Thrones and Minecraft: Story Mode. They do have their own original stuff as well such as The Wolf Among Us.
However this method is often slated by consumers, people do not like the idea of paying separately for the episodes as they feel like it's just a money grab. They'd prefer to pay for the one episode and receive the others free as they come out.
This is a method that requires you to pay a monthly fee in order to keep on playing the games. World of Warcraft uses this method where if you haven't paid for that month in refuses to log you into the game. It is mostly found implemented into large MMORPGs where people will work incredibly hard on their characters meaning people will actually want to pay to keep using that character. Yet again, it is another method hated by the public as it is considered to be another greedy way of obtaining money.