Dark Green Windows 8 Visual Style also works on Windows 8.1, it is based on Nvidia design.
You can use it with any of this icon packs Windows 8 Icon Packs.
TOOLS
OldNewExplorer
WinaeroGlass | winaero.com/download.php?view.… (Enables Transparent borders)
If you wish to get rid of the ribbon use the provided tool Ribbon Disabler for Windows 8, and to use free Startmenu use this app “Classic Shell” Free Customizable Start Menu.