This isn't snarky, it's the right answer! Mavericks prevents opening unsigned apps when you double-click, but Right-Click -> Open will launch a pop-up asking "Are you sure you want to open this?", allowing you to bypass the protection. It's a real thing.
You should allow apps downloaded from places other than App Store. Go to Security & Privacy under System Preferences, and on the general tab, select "Anywhere" under "Allow apps downloaded from:" option.
If it doesn't let you launch, you may need to find the app in Finder and open it from the right click menu. Seems that OS X requires you to do this so that it knows you explicitly want to launch it. It remembers this after the first launch so you can use it normally afterwards.