Catchup time.

16: Where the main character’s arc really should have ended. Games in this series are always released in the same month, for a very specific reason.

15: With a greater variety of weapons and environments, a beautiful soundtrack, an improved cast, and a surprisingly excellent multiplayer segment, this game is considered one of the best sequels of recent years.

14: This studio has not had a misstep for a very long time, and this game showed once again their extraordinary range, by demonstrating that they can make a serious game just as well as a humorous one (indeed, better).

13: This game’s predecessor was loved by all initially but eventually left a sour taste in people’s mouths. This game was just as well loved as release, and still seems to be very well loved.  

Sounds like you're talking about RTS as the genre in which case it'd be Dune II.

But I don't remember anything Tower Defence related so I suspect it's an RTS that had Tower Defence maps like Starcraft or Age of Empires II?

Catchup time.

15: With a greater variety of weapons and environments, a beautiful soundtrack, an improved cast, and a surprisingly excellent multiplayer segment, this game is considered one of the best sequels of recent years.

14: This studio has not had a misstep for a very long time, and this game showed once again their extraordinary range, by demonstrating that they can make a serious game just as well as a humorous one (indeed, better).

13: This game’s predecessor was loved by all initially but eventually left a sour taste in people’s mouths. This game was just as well loved as release, and still seems to be very well loved.  

You're so close so I'll just give it to you: WarCraft III: Reign of Chaos. Gave birth to MOBAs and its custom TD maps were also among the most popular.

15- Uncharted 2?

14- The Last of Us?

Since the last four were so easy, here's a slightly harder one:

    12: An extremely pleasant surprise with a brilliant mindfuck of an ending which set up a great backstory that was kind of ruined by later games in the series.