10 Amazing Video Games With ONE Infuriating Enemy

On the streets of City 17 Gordon Freeman has the patrolling forces of the combine to deal with, but once he hits the underbelly and surrounding areas, Headcrabs become all too common. Hiding in every nook and cranny waiting to pounce - they're essentially Half Life's version of a Face Hugger.

Valve at the time was trying to show off their shiny new Source engine and what it could do, so Half-Life 2 became the poster child. Physics where a huge focus this time around which meant whenever possible Valve would cram levels with stuff for Gordon to smash with his trusty crowbar, but really these served as trusty hiding spots for Head Crabs.

Now, once Gordon has mastered smacking them out of the air as if he was setting up for a home run, the poison variety decides to show up - or in most cases, their terrifying rattle will be heard. Just like that, a single attack will bring Gordon down to one hitpoint, leaving him extremely vulnerable to other attacks. His health will eventually start to regenerate, but if caught off guard, you'll wish wish you never went to Ravenholm.