Yes, I think Metro: Last Light is another in the Metro series. Don't know if it's an official sequel or a "successor" (like Red Dead Redemption was to Red Dead Revolver).
XCOM is a remake of the old turn-based hex combat slash RTS game. Kind of hard to explain the original; you'd probably get a better idea just reading the wikipedia entry or something. But this remake is apparently a FPS with strategy elements blended (such as which missions to take, which tech to research, etc.). Of course, purists will say the remake is an adulteration not worthy of the name, but then people said the same thing before the new style Fallout games came out and they turned out to be perhaps the best games ever made.
Star Trek, I was excited that it would be an action/adventure with RPG elements and Privateer-like branching mission options and quests, but after seeing a few gameplay trailers it looks like a straight FPS. Don't know how you turn Star Trek into an FPS, and there is a lot of material to make a good action/RPG, so I hope I'm wrong.