Players control Gordon Freeman, who travels through the mountains surrounding City 17 to a resistance base with his ally Alyx Vance.

Like previous games in the series, Episode Two combines shooting, puzzle-solving and narrative elements, but adds expansive environments and less linear sequences.

As with previous Half-Life games, Episode Two is played in the first person as Gordon Freeman against transhuman troops, known as the Combine, and other hostile alien creatures.

Others are optional tricks or feats the player can perform, such as killing a Combine soldier with their own grenade or running down a certain number of enemies with the car.

The Hunter is a powerful and resilient enemy which players must often run from while seeking a means to fight back; Episode Two's environments are designed with this in mind.

Hunters are vulnerable to all weapons, but to compensate, are still quite resilient, making explosives and the pulse rifle's charged energy ball the most attractive options.

They introduced more varied gravity gun "ammunition", such as logs, flares, and half-height butane tanks, which are easier to aim than full-size fuel drums.

A homing unit is also installed so the player can quickly locate the car in the chaos of the final battle via a readout in the Hazardous Environment suit.

The two proceed to a transmission station, where they make contact with Dr. Isaac Kleiner (Harry S. Robins) and Dr. Eli Vance (Robert Guillaume), who have arrived at the White Forest rocket facility.

A vortigaunt (Tony Todd) leads the two to an underground outpost, where Gordon is instructed to help gather larvae from a nearby antlion colony to heal Alyx.

He reveals that he rescued Alyx from the Black Mesa Incident despite objections from an unspecified third party, and it is imperative she reaches White Forest.

After Alyx recovers, they reunite with Eli, Kleiner and Dog at White Forest and are introduced to Dr. Arne Magnusson (John Aylward).

After Gordon subdues a Combine attack on the facility, Alyx gives Kleiner a message recorded by Judith Mossman (Michelle Forbes), which contains the location of the Borealis, a vanished Aperture Science research vessel.

[9] An announcement was made on July 13, 2006, stating that Episode Two would be released on Xbox 360 and PlayStation 3 in addition to the PC, where previous iterations of the series separated.

According to Valve's marketing director, Doug Lombardi, the Xbox 360, PlayStation 3, and PC versions would be identical in functionality and performance.

[17] As part of The Orange Box compilation, Episode Two shared with Portal and Team Fortress 2 in winning "Computer Game of the Year" at the 11th Annual Interactive Achievement Awards.

[25] Dan Adams of IGN rated the game 9.4 out of 10 and praised its improved visuals and expansive environments, but cited the short six-hour length as a drawback.

[19] He said: "Any way you look at it, Episode Two stands out, even among the Half-Life series, as something special ... a burly experience packed into roughly six hours or so that offers up all the diversity, level design, and thoughtful gameplay we've known while making sure to propel the story forward and leave us wanting more.

[23] Computer and Video Games said that although the Source engine was dated, the "wonderful art design and the odd bit of technical spit-shine ensure that Episode Two [...] doesn't lose any of its wow factor".

They also noticed that the game "goes about fixing a lot of the niggling complaints we had about Episode One," applauding the open forests and rocky hills.