10 Terrible Boss Fights That Almost Ruined Video Games

7. Kai Leng - Mass Effect 3

Depending on who you ask, Mass Effect 3 might've been ruined by its infamous shambles of an ending.

Though in pure gameplay terms, there's one boss fight which left many players putting the controller down and heading off for a long walk to blow off some steam.

Your final fight with Kai Leng in the Illusive Man's office boasts all the cinematic sheen and intensity you'd hope for, but it's also a prolonged slog for the most part.

For starters, Leng is extremely fast and defending against his close-quarters attacks is extremely difficult - him being a ninja and all - yet even if you try to engage him from a distance, he'll inevitably hurl some irritatingly powerful cronies at you.

Even downing Leng's shields requires a near-Herculean amount of effort, and actually making it through the battle necessitates a sure mastery of your abilities and team management skills.

Despite how cool a villain Leng was, this was ultimately more frustrating than fun, and put a sizable dent in the game shortly before the ending arrived and really pissed everyone off.