Ok, the "Top Secret" box. That's the stretch goals from the expansions Ks campaign.
Like I said in another thread, most of that stuff, but not all, you won't be adding to the core game. Let me see if I can break it down...
You can use NPCs in the core set, but it will make the missions easier unless you increase the difficulty somehow.
You can add the vintage weapon sets to the improved weapons' stack, as well as a few of the KS exclusive skills to the skill's deck.
You can also use some of the new agents with the core game I think. You may have to introduce new mechanics from the expansions to do that though, like psionics to use Niobium.
The main thing that I personally would add to the core campaign would be the fighting poses variant. They add a nice touch.
There might be a few other things, but I don't see it at first glance. I think that if you want to get the expansions, then getting the "top secret" box as part of the expansions package is great. Just a warning... you will get overwhelmed with all the additional content. I know I did, and I had already played through the core box. But overwhelmed in a good way! So... much... stuff!!
hehe..yes theres plenty of stuff in the core box alone!!..I think I will go for the two expansions played first two missions solo today.and the AI system on the aliens is the best ive been against thanks for the info