Half-Life 2 is hardly revolutionary, despite all of Valve's marketing attempts to make you think otherwise. It is Half-Life with physics, nicer graphics and tighter level design. Is this bad? Not on your life.
Truth be told, other than Valve greatly exaggerating the effect physics will have on gameplay, there's little to complain about. Sure there are nitpicks and some of them are even worth mentioning, but I could just as well spend the rest of the article explaining how tightly orchestrated an experience Half-Life 2 is.
In fact, that's about the only knock that can be made on the game - it is very linear. Not as claustrophobic and rail-like as Doom 3 or even Call of Duty, but there's no disguising that this is a very, very linear game. However, it is precisely that linearity that permits it to be so impressive. The scripting is tight down to the last second, it hardly ever hits a fault no matter what the player does.
There are compromises made, such as certain NPCs being unkillable, but don't expect Barney to lead you through an entire level while you sit back and collect ammo. Valve has permitted the player to interact with rather basic groups on two occasions. On one map, Gordon has access to a colony of some very lethal Ant Lions. He can summon them almost anywhere on that map and command them to attack certain objectives or follow him. In the city, at several points our hero is joined by nameless rebel NPCs. These guys aren't nearly as useful as ant lions, but they do provide a very stirring sense of realism. Like the AI, they react to grenades, take cover and fire decently. The medics will even give out health packs to the NPCs and Freeman.
And yet, though this is completely subjective, it seems as though Half-Life 2's AI is much more dependent on level design and proper scripting than Halo 2's AI is. In Halo 2, the AI - both enemy and friendly - seemed considerably more competent and friendly. Valve's coding shows a touch too much rigidity in AI behavior. It spots the player too easily, it's too insistent on firing certain weapons beyond their effective range, like the SMG, instead of closing in, unlike Halo 2.
However, there's far more similarity between Halo 2 and Half-Life 2 than differences. AI and teammates both chatter. Of course, the difference is that in Halo 2 this is mostly for comic effect and atmosphere. Half-Life 2 takes itself far too seriously to permit even the gentlest humor into the game during action, and the talk from Combine forces is menacing, right down to their modulated voices.
Killing a Civil Protection trooper, for example, sets off a loud (and remarkably annoying) alarm, followed by a broadcast report from what sounds to be a dispatcher. She reports the death and sometimes location, and instructs troops to contain. Valve should definitely have spent the extra change to get some more variety in the speech, however.
The similarities extend to gameplay as well. Both games are very linear but try not to make this obvious by not constantly pointing an arrow in the proper direction, but the end result is the same. Doors are locked, paths are barred, and only one route remains. Yes, the player has to discover it, but that doesn't make it any less linear. In fact, many routes won't open until all the enemies in the room are killed - a la Halo 2. Valve manages to set up some interesting fights and disguises the fact that this is a room-by-room sweep most of the time. For variety, there are boat and buggy levels thrown in, as well as sequences which have Gordon running rather than running and gunning.
The game makes it very
obvious at what points our dear Dr. Freeman is supposed to fight a Strider or Gunship. There will be an RPG launcher ready and a crate of unlimited RPG ammo nearby, and the map won't progress until the Strider(s) or Gunship(s) are dealt with.
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