64MER ZONE reviews Killzone 2 by comparing it to World War 2 shooters:
Nazis in Space
When ideas grow old and repetition gets tiresome, when all hope seems lost, there's only one thing left to do: turn to the infinite void of space to spice things up a little. It worked for Super Mario, and it works for World War 2. Instead of invading Nazi-occupied Europe, you're invading the planet Helghan. The large battleships that stormed Normandy turn into Vekta cruisers. Instead of landing on enemy soil in a wooden boat, you do so in a flying tin can. The 'take out the anti-air turret' mission becomes the 'take out the lightning cannon' mission. The 'lower the bridge' mission becomes... well... I guess there's no real reason for bridges to be any different on other planets.