Most games pause when you leave. Sectorum doesn't. The galaxy is a living system — every player's trade, attack, and colonization affects every other player, whether they're online or not. This creates the most important property of great MMOs: your decisions have lasting consequences.
Claim a sector and it's yours — until someone takes it from you. Establish a trade route and profit from it — until someone undercuts you or the port supply runs dry. Form a corporation and build an empire — and feel the weight of having real allies who are counting on you.
This is the design philosophy that made TradeWars 2002 legendary, and it's the same philosophy that drives every decision in Sectorum.