Kirby's Adventure

Metroid
-Metroid Prime

Half Life
-Half Life 2

Metal Gear
-Metal Gear Solid 4: Guns of the Patriots

Pokemon
-Pokemon Emerald

Mega Man
-Mega Man Battle Network

Uncharted 2 > Uncharted 3 > Uncharted DF

God of War 3 > God of War 2 > God of War > God of War Ascension

Lol I played GoW totally backwards, I played GoW 2 temporarily at a friends house first, but that's the order I've bought them in

my favourite series is Metroid as well, and the first game i plated in the series was the first Metroid, but on the GBA. Bought it from a bargain bin in WHSmiths for £5 when i was about 13 - was boxed & perfect condition.
I completed it that week and bought Metroid Fusion - my favourite game in the series

Metroid Prime 2 and Mario Kart: Double Dash.

Oh, and Pokémon Red and Zelda: Twilight Princess. 

The Legend of Zelda. It changed what a video game could be.

The Legend of Zelda.

First game I played was A Link to the Past.

Brilliant game, but now it only stands at fifth place for me in the series because after it, even better games came. My favorite is Ocarina of Time.

Final Fantasy X
Halo 2
Ratchet and Clank
Star Ocean: The Last Hope
Persona 4

If played the first Legend of Zelda game and I didn't like it.
Then I played Wind Waker.