Killzone 1 is, Killzone 2 is not and Killzone 3 is.
Only in online.
There are currently four (4) KillZone games for the PS3. KillZone is the original game, it is for PS2. There are also two (2) more games for the PS3, KillZone 3, and KillZone 2. There is also a a game for the PSP, KillZone: Liberation. There is most likely going to be at least one (1) more game, probably for the PS3.
yes
yes you can play Move two player
Killzone 2 is one player (offline) and 2-32 player (online).
Absolutely, KILLZONE is split-screen for multiplayer. one screen on the top and another on the bottom. to guy above... where did you get that info? killzone 2 has NO SPLITSCREEN at all... im pretty sure your talking about the 1st one.
The answer really depends on the player. Army of Two is for a polayer trhat wants a really good challenge, because the controls are very difficult and so is trhe gameplay. Killzone two's controls are simple, but it provides some of the best gameplay during the campaign and online. Killzonme two got a 5/5 rating. For me I think killzone two is better.
Yes
Sadly, no it does not. KillZone 1 does have an campaign, but it is only one (1) player. If you wish to play KillZone with a friend, I suggest KillZone 3. It has both a single player and multiplayer campaign, with an online mode as well. A great choice if I do say so myself.
KILLZONE
Killzone 3
Online?