Campaign mode is single player only. Only SpecOps allow 2 players splitscreen or online 2 players. When you play 2 players online, each one has the PSN ID. For 4 players, you have to play online which means you need to have 4 PS3 consoles with 4 copies of MW2.
There are very few games today that have campaign with 2 players. Most games are designed to play online if you want multiple players. Gears of War and Halo are 2 players splitscreen campaign but on X360.
My guess is most game developers don't want to bother design local multiplayers splitscreen. Only games like Ultimate Martel Alliance is designed for 4 players splitscreen. Fighting games are always 2 players capable.
Campaign mode is single player only. Only SpecOps allow 2 players splitscreen or online 2 players. When you play 2 players online, each one has the PSN ID. For 4 players, you have to play online which means you need to have 4 PS3 consoles with 4 copies of MW2.
There are very few games today that have campaign with 2 players. Most games are designed to play online if you want multiple players. Gears of War and Halo are 2 players splitscreen campaign but on X360.
My guess is most game developers don't want to bother design local multiplayers splitscreen. Only games like Ultimate Martel Alliance is designed for 4 players splitscreen. Fighting games are always 2 players capable.