So I just started playing the game and after the very first mission you are on the helicarrier and can do free play and return to past mission on it and all, but after I went to Manhattan I've done 2 missions and can't find a way to get out of story mode, do I have to beat the game in order to be able to have the city open and go back to it?

I feel you dude this site sucks I used to have gamespot as my homepage, now its all broken, not helpful, the searchs are horrible, i just tried to look for new releases on xbox 360 and I got halo 3 as a result and a bunch of old games (WTF?!!) no more search by score, or genre its just terrible why fix whats not broken?, and in this case why brake what was not broken...