I played the demo. I've looked at screenshots online. It looks like the only guys you ever fight are the guys with the glowing red eyes. Is that true, or are there other enemy types?

Hey Brian! I don't know the answer to your question, but its good to see you.

Contrary to the letters under my name, I am indeed still alive (as of this message, anyway).

well seeing that the events of the Killzone series take place during a war and the enemy is a proper military and not militia the enemies would have a common uniform making them all look alike and the bulk of their military would be basic infantry grunts...

so basically speaking... for the majority of the game you will be shooting standard Helghast soldiers

there are some variants and other enemy types... i didn't get very far in the single player when i rented the game (spent most of my game time online) but i certainly remember some heavily armored ******* fairly early in the game

I don't know anything about the story, I never played the first one. So they are humans then? I thought for some reason I was fighting against aliens. Hrm.

the short version... the Helghast are humans that colonized a planet with extremely harsh conditions and over many years have adapted to the harsh environment... they look like normal humans the main difference on appearance is they are all white (and i mean white... they are all quite pale when you shoot their helmets off)

You'll usually be fighting against standard Helghast, but they still prove to be quite a challenge.

There are a few boss fights, which consist of the heavily armored enemies that DrkJedi82 mentioned.

The game's great, anywho. I haven't played any other of the KZ games, but this was still quite wicked. I also didn't need to know all too much about the first games in order to understand what was going on, but that might depend on who's playing.

I especially love the level that takes place on the space station (Vekta I believe). Was my favorite.

There are a couple different bosses where you have to shoot their helmet then gas tank, some floating sentry bots, the odd tank, a futuristic enemy helicopter (bull****) and the final boss (total bull****).

A few months ago, I didn't want to buy Killzone 2, so I decided to buy Killzone: Liberation on PSP instead (A top-down shooter...strange concept but it was actually a really good game/felt like I was playing an FPS).

I don't know if this answers your question, but in KZ:L enemies had yellow eyes if they were patrolling, orange if they were alerted, and red if they knew where you were/were in combat mode.

EDIT: Re-read...
Well in KZ-L there were a few different enemy types. Robot Dogs, spider-like mines that slowly walk toward you and explode when they get near or are shot first, and a few bosses. The different red-eyed dudes had different weapons, like rocket launchers, machine guns, sniper rifles, etc.