As you will no doubt recall, Valve decided to go the episodic way with Half Life 3 (HL3) since they took nearly five years to develop Half Life 2. By breaking HL3 into three distinct episodes, Valve has significantly reduced the waiting period for future Half Life installments.
Besides that, creating this sort of episodic content not only allows Valve to improve their content, but they can even polish the game to make sure it does not seem graphically archaic in today’s day and age. And that's a welcome deal.
Now I know the Source engine may pale a bit in comparison to that of Crytek 2 Unreal 3, but Episode 2 packs in enough graphical bells and whistles – cinematic physics, soft shadows, killer lighting, HDR and the like – to impress the graphics whore within.
Not only does the game look a whole lot better than either HL2 or Episode 1, but it runs pretty well on mid-range rigs as well, courtesy of the Source engine’s scalable nature.
If you've forgotten the events that transpired in Episode I, there’s a nice little recap waiting for you before the game begins. Once you’ve been updated with the storyline, it’s up to you to make sure that Gordon and Alyx reach the allied base at White Forest safely.
Obviously this isn’t going to be a walk in the park (or forest) and you’ll encounter tons of 'problems' on the way, none of which should pose too much of a threat considering your badass arsenal of weapons taken from previous iterations.
While there are no new weapons to be found in the game, you’ll come across a couple of new foes like ant lions (that spew acid) and Combine hunters (mini-striders of sorts that don’t go down easily). But worry not; for nearly every major battle, you’ll have some sort of support in the form of Alyx, Vortigaunts or the usual allied soldiers who thankfully aren’t as brain-dead as those from Half Life 2.
truely a great game and me a big fan of hl2 series recommends a 8 series video card to observe the power of the game engine in episode 2 
