This emulator stresses speed and offers very few options for customizing it, to the point that you can't even change the resolution or adjust any parameter except those found on your Android's own Settings panel. But when it comes time to play, the breakneck emulation speeds (which don't require any configuration) make up for this paucity of features. Just install the program, sync it with your Google account, and start using it.
LeapDroid is a good emulator that, like most of its competitors, runs a virtual machine in the background. However, this tool does sacrifice extra features so that your apps can run fluidly, even if they're more demanding in terms of their graphics processing.