Well I don't really see any other left-wing parties in the race. The Conservative Party are right-wing, the Common Sense party claim to be libertarian (I don't really see how they're libertarian though) but they're certainly not left-wing, the IUP are centrists with a libertarian leaning but they lean left about as much as they lean right, and the Republican Party of the Atlantic is basically a 2nd version of the Holy Crusader Party who were right-leaning libertarians. R.O.T. looks like the only option for left-wingers.
The Common Sense Party is basically a continuation of the Libertarian Alliance but this time left-wingers like sloth or SuGas don't seem to have as much influence. The party looks like OlympianProduct's brainchild (which is why I think it's ironic how he calls it a libertarian party since OlympianProduct's moderation history seems to show that he's anything but a libertarian).