It's like Seven Samurai because its about a small group of warriors who seal themselves off in an enclosed civilian outpost to fight off wave after wave of oncoming enemies with overwhelming numbers. That's the basic thrust of Samurai, and Aliens too. You also have the use of maps to orient planning and fortifications (blueprints in Aliens, dirt drawings and paper maps in Samurai), booby traps to help even the odds, and other similarities like that. Obviously they are different films, but they have a ton in common.