I was recently asked whether or not it was more effective to start out a 3D Online RPG engine by creating all of the engine pieces from scratch, or use already created free, open-source libraries. These pieces include a graphics rendering engine, networking engine, audio engine, physics engine, content engine, and each of these component's sub-parts.

The project in question was to be a small 3D Online RPG game that would be released to the public for free yet have a monthly subscription fee.

So the questions I have are:

Do free, previously coded and open source game engine libraries usually allow their creations to be used in projects that charge a monetary, monthly fee for their products?

Are these free open source game engine libraries easily integrated and combined with each other in a project?

Thanks in advance!

There is an enormous difference between MMORPG and ORPG.

For an MMORPG, you are going to invest several million dollars in external software packages. Don't worry, that is only a drop in the financial bucket of an MMO, which will run into the hundreds of millions of dollars and require a staff of several hundred people to complete.

For an ORPG, you can use an engine or not as your preference. The networking forum FAQ has an example of getting a minimal 2D ORPG minimally functional in just a few hours.

There is a mantra "make games, not engines" that applies here. You can choose to spend your years rewriting vector libraries, rendering libraries, resource management and caching libraries, audio libraries, animation libraries, simulation libraries, networking libraries, and all the necessary server architecture of database backends, user authentication, persistence, game data validation, and all the rest.... Or you can spend your time creating and hooking up content.

Many engines allow you to charge money for your game, a few do not. There are many to chose from so read the license agreements as part of your evaluation of the products. How well they integrate with each other will vary widely, again, check for the specific libraries you are interested in.

Thanks, I accidentally wrote MMO on the subject. I appreciate the information. The way I see it is that it would be better, like you said, to spend time creating and hooking up content than to spend years creating and modifying engine libraries, in this situation.

Resellable. Looking further into it, there are multiple open source engine libraries out there that are under the MIT license, which means that I can sell whatever I make with them as long as their license file is included with the product.