At this point, I assume that you have a fresh installation of Unity and have started it. You can perform the following steps:
- With Unity started, navigate to File | New Project.
- Select a project location of your choice somewhere on your hard drive and ensure that you have Setup defaults for set to
3D. Then, put in a Project name (I used First Person Shooter):
- Once completed, click on Create project. Here, if you see the Welcome to Unity popup, feel free to close it as we won't be using it.
Now just because we are going to be diving straight into Unity, I feel that it's important to talk a little more about how level design is done in the game industry. Although you may think a level designer will just jump into the editor and start playing, the truth is that you normally would need to do a ton of planning ahead of time before you even open up your tool.
In general, a level begins with an idea. This can come from anything; maybe you saw a really cool building, or a photo on the Internet gave you a certain feeling; maybe you want to teach the player a new mechanic. Turning this idea into a level is what a level designer does. Taking all of these ideas, the level designer will create a level design document, which will outline exactly what you're trying to achieve with the entire level from start to end.
A level design document will describe everything inside the level; listing all of the possible encounters, puzzles, so on and so forth, which the player will need to complete as well as any side quests that the player will be able to achieve. To prepare for this, you should include as many references as you can with maps, images, and movies similar to what you're trying to achieve. If you're working with a team, making this document available on a website or wiki will be a great asset so that you know exactly what is being done in the level, what the team can use in their levels, and how difficult their encounters can be. In general, you'll also want a top-down layout of your level done either on a computer or with a graph paper, with a line showing a player's general route for the level with encounters and missions planned out.
Of course, you don't want to be too tied down to your design document and it will change as you playtest and work on the level, but the documentation process will help solidify your ideas and give you a firm basis to work from.
For those of you interested in seeing some level design documents, feel free to check out Adam Reynolds (Level Designer on Homefront and Call of Duty: World at War) at http://wiki.modsrepository.com/index.php?title=Level_Design:_Level_Design_Document_Example.
Note
If you want to learn more about level design, I'm a big fan of Beginning Game Level Design, John Feil (previously my teacher) and Marc Scattergood, Cengage Learning PTR. For more of an introduction to all of game design from scratch, check out Level Up!: The Guide to Great Video Game Design, Scott Rogers, Wiley and The Art of Game Design, Jesse Schell, CRC Press.
For some online resources, Scott has a neat GDC talk named Everything I Learned About Level Design I Learned from Disneyland, which can be found at http://mrbossdesign.blogspot.com/2009/03/everything-i-learned-about-game-design.html, and World of Level Design (http://worldofleveldesign.com/) is a good source for learning about of level design, though it does not talk about Unity specifically.