Unity 5 is out (and more handsome than ever, check out that moustache!).
It's chock-full of all sorts of super-fun stuff that you (and I, and everyone else) want to try out.
If, like me, you're a bit paranoid and don't want to jeopardize your existing development environment, the good news is that you can install and use multiple versions of Unity side-by-side, completely independently.
Backup your current Unity projects
First of all, make backups of any projects that you're planning to try in a new version. If you're a good, responsible developer (of course you are) and have your code stored safely in a repository like GitHub already, you can go ahead an skip this step since you can always revert if things break catastrophically.
Install the new version of Unity
- If you're using a Mac:
- Locate your existing Unity installation (the default is /Applications/Unity) and rename it to reflect whatever version it is (e.g. Unity-4.6.1).
- Install the new version of Unity as you normally would.
- If you're using a PC:
- The Unity installer will automatically choose the existing Unity path. If you simply change the installation directory to a different path, you should be good to go.
Safely loading your Unity projects
Regardless of the platform you're developing on, both new and old versions of Unity will load the last project that you opened by default, which means that if you run the new version of Unity just by clicking the shortcut, it will open and upgrade your most recent project. If you're just looking to experiment with the new version, that's probably not what you want.
To avoid all that, hold the ALT key when launching either version Unity to get a list of projects so that you can pick the one that you want to load.
Also if you have any Unity shortcuts (either in the dock / start bar or on your desktop), you'll probably want to rename those to better reflect which version they now open.