Game Breaker / Overwatch

• During the second beta test, Bastion and Torbjörn were the biggest. In the first beta test, they had a reputation as being overpowered against newer players, while almost useless against highly skilled/experienced ones. Blizzard attempted some major changes on both of them, which resulted for a time in Bastion being extremely difficult to kill with high hit points, damage, and self repair, and Torbjörn's turret being high damage, enormous range, instant lock on, able to kill just about anything peeking into its sight for too long. Further balance changes put things in better shape, although both characters still have rough edges.
• Widowmaker was widely decried as far too powerful on release, when her sniper rifle did absurd damage and reached full charge in a second, allowing her to double-tap almost every single non-tank hero in the game without any risk of them retaliating, and even her unscoped rifle was a surprisingly effective weapon up-close, making flanking her dangerous. It's telling that the only counter to a good Widowmaker was considered to be another Widowmaker (or a Winston, whose main purpose is to counter squishes like her). She also eventually got a nerf, lowering her damage and ult charge rate, and since then she's become rather low-tier, even in professional levels, but players prefer that over being as horrendously oppressive as before.
• Bastion became one again at the Season 4 launch, after it was tweaked for more dynamic options after it turned into a rather niche Skill Gate Character. It worked way too well, and as detailed on the Tier-Induced Scrappy page, games instantly became based entirely around Bastion's ridiculous DPS and Nigh-Invulnerability whose only reasonable counter was another Bastion, to a point that Blizzard had to issue a hotfix nerf 3 days after the change.
• In the open beta, we had Mei. Her primary fire had a surprisingly long range and froze enemies, lining them up for a perfect headshot from her pinpoint accurate secondary fire, basically spelling a one hit kill for anyone not a tank. On top of that, her Ice Wall had infinite range (limited only by line of sight) and had such a short cooldown time its easily spammed to stall out pushes, though it eventually died down as most players learned how to get used to get used to her and began favoring other heroes.
• McCree had the infamous Flashbang-Fan the Hammer combo, which was basically a stun and free 420 damage if all of its shots connected, something very easy to do on a sitting duck. This combo effectively killed anyone who didn't have a shield or armor buff nor is a tank, and even that didn't guarantee safety, as McCree could just roll for an instant reload and then use FTH again to finish off the victim. The damage of Fan the Hammer eventually got nerfed to 270 damage if all the shots connect, allowing it to still be a solid squishy-busting tool but not as overwhelmingly effective against tanks.
• Multiple Törbjorns on consoles, due to the slower aiming speed making them far harder to take down rapidly while they still retain their instant lock-on and high damage. Unsurprisingly, Blizzard hit Törbjorn with a pretty massive damage nerf only on consoles (and later hero stacking across the entire board) because he was just that game-breaking.
• Ana, during the initial release of Season 2. Ana's Ultimate charge speed, combined with nerfs to Zenyatta's Orb of Discord, created a very broken system where no other characters were viable except Tanks and Supports because it is far more efficient to get Ana up to maximum charge as quickly as possible, whereupon a Nano-Boosted Reinhardt (maybe a Genji or Reaper) deals more damage than the rest of the team combined. This also means that dedicated Offense/DPS characters were a liability because all they did was feed Ana. Not every pro team was using this team comp, but those who weren't were dedicating a lot of effort to figuring out how to counter it. To quote the analysts at Overbuff.com:
  "The end result is that by releasing Ana with her present ultimate charge rate, the Overwatch devs have indirectly (and probably accidentally) made the same mistake they made in early closed beta – promoting a game state where players are afraid to actually play the game."
• The initial version of the Season 6 Mercy rework made games borderline-unwinnable for teams that simply didn't have her. Despite being only single-target and based off a hefty 30-second cooldown (which could've been reset/reduced thanks to her new ultimate), her infamous Resurrect was still extremely powerful, and when combined with everything else in her kit and her low-skill floor, she became ridiculously all-encompassing for her job at all skill levels, all while being incredibly obnoxious for the enemy team to fight against, basically requiring she be played in every single game by every team. She was eventually nerfed into something far more manageable after several months worth of patches and light retools, primarily to her Resurrect.
• Hanzo's Scatter Arrow, initially intended for dealing damage around corners or in corridors, turned into a "free kill" ability as it was extremely easy to just point near an enemy's feet and bounce all three arrows into their body, killing anything that wasn't a tank. Scatter moved so fast and had such wide range, it was nearly impossible to avoid even when trying. It was eventually replaced with Storm Arrow, which requires more aim and takes longer to kill.
• The "GOATS" strategy in competitive play is widely considered to be the most difficult-to-defeat team composition in the game's history. A North American pro-team named GOATS (hence the name) came up with the idea of simply dropping all damage characters from their roster, and instead running three tanks and three healers. The result was a team of complete Lightning Bruisers, with any team running this comp being mobile, tanky, and even damaging if certain tanks like Reinhardt and Zarya and certain supports like Zenyatta and Brigitte were chosen. Blizzard then spent the better part of a year trying to systematically murder this team composition, nerfing its main enabler (Brigitte) repeatedly, buffing tankbuster DPS like Reaper and Mei, nerfing the tanks (Rein, D.Va and Zarya, particularly), and even wholesale nerfing Armor as a mechanic. And then finally by introducing the 2-Tanks/2-DPS/2-Support Role Queue system to outright prevent players from running any GOATS combination. During its heyday, GOATS absolutely terrified the competitive scene of the game and dominated the highest levels of the game.

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