The evil alien hordes in Tabula Rasa don't just sit and wait for you to come hunt them down, either. Certain bases on each game map (called capture points) will periodically fall under assault from the Bane. If no player characters are around to defend them, the capture points will inevitably be taken over by the aliens, and then player characters must launch a counter-attack to get the base back. It's a fun and immersive tug-of-war that ends up being just as at home here as it would be in Quake Wars.
The cloning system continues the quick movement in Tabula Rasa. Rather than start over at level 1 for every new character you want to create, you can quest for cloning credits that allow you to make an exact duplicate of your character at any level. This is especially key since every beginning character starts as the exact same "Recruit" with new class branches offered at level 5, 15, and 30. The new character grind would be significantly worse than in other MMOs, since there are no new classes to experience at the early levels, so the cloning is a brilliant dodge on the part of the developers.