Once you've done that you're off and running. Check your @reply inbox on Twitter because you'll soon receive an assignment to take out a fellow player. To do this, you just go back to the web site and there is a built-in Twitter client where you can choose an action. It ends up looking like this:
@assassins_rome slash @LunabeanMedia.
At any given time, you may find yourself being hunted or being the hunter. At your disposal are a number of weapons and escapes, complete with upgrades as you rise in the ranks of the Twassassins.
If you want more info, you can check out @assassinscreed.