Exploring the Unknown Parts of XCOM: Enemy Unknown

Joystiq has an article on the "unknown parts" of Firaxis' upcoming XCOM: Enemy Unknown, the little mechanics and details we've heard nothing or almost nothing so far, helped by lead designer Jake Solomon and producer Garth DeAngelis. Here's an excerpt:
Players of the original X-COM know that shooting down UFOs and investigating crash sites was absolutely essential to advancement. Taking out UFOs is still "crucially important," says Solomon, though things work a little differently in Enemy Unknown. As I mentioned in my previous article, players won't have to establish new bases to detect alien incursions, but instead launch satellites to cover different parts of the world. "There's a lot of little subtle mechanics to it, but you need to back up your satellite coverage with your Interceptors, and so you need to have jets stationed around the world ready to intercept these UFO contacts." Should you manage to take down a UFO (or if it lands of its own accord), you'll be able to investigate the crash site, kill any surviving aliens, and harvest their technology for research.

Campaign missions are separate from UFO missions. These missions allow the members of XCOM the in-game world's Extraterrestrial Combat Unit to keep the global peace, rewarding players with funds and resources like scientists and engineers. Meanwhile, UFO missions offer more tangible rewards in the form of recovered alien technology. DeAngelis likens UFO missions to finding a treasure chest "a treasure chest full of horrible things that want to kill you," Solomon says.

"It's like a treasure chest for the scientists and engineers, because you get all these different types of resources and loot that are impossible to get on the other types of mission," DeAngelis adds. These resources then leads to research projects that players might not otherwise discover. Solomon notes that UFO missions are the key route for players to recover and adapt alien technology. "There are very, very few other ways to get ahold of alien technology, so you really have to be ready for when that UFO shows up."