I've seen this a lot with barbarians in fiction, even some "historical fiction", especially that which focused on the barbarians that fought the Romans.
Basically, soldiers were clad in metal armor, sometimes it was covered it spikes but not always. Their tactic was to run into a group of enemy soldiers and flail wildly in order to cause chaos and break up a group of soldiers.
Is there any truth to this or is it all Hollywood/videogame fiction?
I don't know what you're referring to specifically, but it sounds unlikely. Medieval knights were clad in metal armor, and they didn't do much running because their armor was too heavy. Also, "flailing wildly" is not a very good military tactic; I think a group of such disorganized troops would be more likely to be the routed than the routers. Finally, a suit of armor was very expensive, so only the wealthiest and most important men had one.