XCOM is a game of resource management and tactics more than a game of chance. I can pretend itís the dice roll that decides who lives and who dies, but itís my decisions. Because I decided to spend money on laser rifles instead of body armor, I had to send an under-equipped soldier on a difficult mission, and I pulled him out of cover to collect Meld for my laboratories. And now heís dead. In that respect, itís more vitally a game about sacrifice, ethics, and responsibility.
Enemy Within muddies up those ethical waters with even more excruciating decisions, requires more complex tactics, and promotes an even deeper connection to the soldiers I dearly want to protect. It doesn't significantly address Enemy Unknownís shortcomings, but adds more great, challenging experiences to an already great game.