Particulars is a game with a unique combination of arcade-action and puzzle gameplay, set in the mysterious world of subatomic particles. Taking control of a single quark, you must negotiate the fundamental forces of the universe. Other particles will push and pull at you – you'll always be on the brink of losing control and being dragged towards annihilation.Go to: http://store.steampowered.com/ and download STEAM client
Click “Install Steam” (from the upper right corner)
Install and start application, login with your Account name and Password (create one if you don’t have).
Please follow these instructions to activate a new retail purchase on Steam:
Launch Steam and log into your Steam account.
Click the Games Menu.
Choose Activate a Product on Steam…
Follow the onscreen instructions to complete the process.
After successful code verification go to the “MY GAMES” tab and start downloading.