This is just an icon pack (not a game!). It works to change the apperance of icons used on your phone/tablet. It is not a standalone app, it requires a launcher program (like Nova, ADW, Next, etc).

In order to apply the iconpack,

1) Make sure a Launcher program is installed (e.g. Nova, ADW, Apex, GO, Next or similar)
2) Open "Traffic" app
3) Hit the blue "Quick Apply" button down in the middle
4) Select the Launcher program you already installed.

or

1) Open your launcher program (e.g. Nova, Action, ADW, Apex, GO, Next or similar)
2) Find the "Look&Feel" (Nova), "Display" (Action), "Themes" (ADW), "Theme Settings" (Apex) or similar for other launcher program on their own "settings" menu
3) Select "Icon Theme" (or similar) and choose "Traffic"