After the invasion it unlocks the hubs, but you have to beat the first missions of those levels to unlock freeplay as well as scenes B and C if I'm remembering right. I thought it was interesting playing the invasion from different starting points wth the other scenes/levels that are added. Haven't played it in a couple weeks though and only unlocked maybe 25 characters or so and I'm around 12 percent done. I was excited to see Jim Hammond/Torch so early on and in his sweet new SHIELD suit and making old person jokes. This Detroit Steel guy is pretty badass too. Looks a little like Optimus Prime though...

~KL~