Demonic Spider: Doom Gems from Bejeweled Twist. They first appear in Level 13 from Classic Mode. What do they do? Well, they basically act as a Locked Gem and a Bomb Gem; you can't move them, and unlike Bomb Gems, you can't match them, so you need to resort to using special gems to destroy them. And that number on top of them? It goes down every time you make a matchless move. This wouldn't be so bad, but at the point in the game you encounter them, Bomb Gems take less than 10 turns to explode, which would make matchless moves a necessity to clear them. And if the counter goes down to 0, it's an instant Game Over. The only saving grace is that they only appear once in each level.
Not to mention that damn butterfly game.
Do Not Do This Cool Thing: Possibly feared by the ESRB, as the development of Bejeweled 3 suggests. The ultra-relaxing Zen Mode was not only intended to relieve stress, but also to suggest different things to help smokers quit their addiction. Unfortunately, that part didn't make it to the final product because any game that so much as mentions smoking,whether positively or negatively, would end up with a restrictive rating mentioning "tobacco use" and rather than the otherwise-appropriate "E" rating.
The butterfly game is unwinnable. No matter how slowly and carefully you play, the spider always wins. Not to mention that in the mobile versions, the Spider will taunt the player by appearing close-up on the Game Over screen from above.
The games in general are really good at inducing panic in certain modes when the player is close to defeat.
Bomb Gems and Doom Gems in Twist have unlimited potential for messing up your playthroughs, and hearing their respective sounds is very harrowing.
In Butterflies mode, a butterfly swapping with a hypercube automatically triggers it, often before you're able to use it at a better time!
Also, butterflies spawning at the bottom of the screen can replace special gems that have fallen there. Good luck saving the butterfly at the top now! Thankfully this doesn't apply to hypercubes.
In Twist, it's impossible to make counter-clockwise turns, even when they'd be beneficial. This often leads to matchless moves and decreasing your accrued score multiplier. Fortunately, the Twist mode in Blitz LIVE allows counter-clockwise moves.
That One Achievement: Getting Flushes in 3's Poker Mode for the Gambler badge. A Flush requires that you match the same color of gems for all 5 cards (although if you match 5 gems with one move, it counts as whatever color is the most optimal for the combination- if you do so after getting four of a kind, you'll get a Flush), which, due to the randomized gems, is quite fittingly a Luck-Based Mission. That's before you factor in how many you need to get; 10 just for the base Bronze badge, all the way up to 100 for the Platinum tier. Only about 15% of the playerbase has the Bronze achievement, and 3.4% has the Platinum achievement, making it the second least-completed achievement after Ice Breaker: Platinum (which has a rate of 2.2%).
That One Level: The Gold Rush mini-quests, which require the player to dig underground by scoring matches right next to dirt and collect gold by scoring matches right next to buried gold (not to mention bedrock tiles that require multiple matches to break through.) It can be insanely hard to pull down gems to the bottom level, and the ensuing uneven terrain can screw with your ability to swap gems. On top of that, the whole thing is timed, hindering your ability to think tactically (which is an absolute must on a mini-quest like this.) On higher difficulties, the whole thing becomes little more than a Luck-Based Mission (even moreso than other game modes.)
that ensues. They're just so adorable!