来自老外的一个简单2d射击游戏示例，学习整理发布下。先来个简介吧！

This tutorial shows you how to add an enemy object to the simple 2D Shooter project located here, which requires at least version 2.0 of Unity to work. It's not an in-depth look at actually creating such a game, but rather an example of working with a Unity project and some additional scripting. Thus it might help relative beginners with Unity to see an example of how a project can be structured to be easy to work with and extend, though it does assume some basic familiarity with Unity's functionality, and the scripting discussion assumes basic knowledge of programming concepts and terminology. The code in the project that already exists isn't covered here, but it's reasonably well commented, in an attempt to explain the thought processes behind creating a 2D game in Unity. (Not all thoughts are guaranteed to be 100% correct or sane.  ;) )

本系列教程将向你展示如何添加敌人到一个简单的2d射击项目中，此项目源文件需要unity3d2.0以上版本打开。（我用2.6撕开，出现脚本错误，还好不影响程序运行）。在此并不深入探讨如何建立一个完整的游戏，此教程及项目只是一个利用unity3d工作的简单示例，并包括少量的脚本代码，通过此示例使初学者对unity3d项目的构成及运行扩展有一个初步的了解。当然，开始工作前，你需要具备一些基础的能力，如对unity3d基本的操作，及其脚本知识的基本了解（未完）

If you get stuck or confused, you can use the project located here as a reference for the tutorial. It's the same as the project from the above link, but it also includes everything from the tutorial up to but not including Part 7, section 4 (wouldn't want to take away all the fun!).