Throughout my time in playing D&D 3.5, there have been a number of foibles that rear their ugly heads again and again. House rules tend to try to fix these types of issues, but a player/DM can only house-rule against insistent power-gamers for so long until it becomes time to find other people to game with. And it seems I'm not alone in this matter:
Jason Bulmahn wrote:
The 3.5 rules set is excellent, but it has its flaws. Over the past few years, a number of common problems have seemed to crop up again and again, problems that delay the game or cause no end of arguments....
Perhaps a list of game-breaking or game-grinding issues would aid Paizo in creating a Pathfinder RPG that people would be generally happy with. Even if it wouldn't, I'd be a bit interested to hear what has broken your games to a point of extinction.
Some of the issues I've ran up against are the following, as both player and DM:
Polymorph - So much errata, and with so much material to draw from it becomes a game of "What's the perfect solution to this encounter" or "I know the rules better than you". The spell hasn't in so much broken a game as it has grinded a number of games to a halt.
Custom Wonderous Items - This often starts innocently enough, with a player wanting another ability that isn't covered by their options already. Unfortunately, the Estimating Gold Piece Values table is utilized/argued as formula rather than educated guess-work, and an unforeseen consequence slips by the DM; that item or precedence of the item might ruin a plot-line or skews the power level so much that the game becomes virtually unplayable.
Telejack - The Scry/Teleport combo abused. Scry on a target constantly until he fails, then (likely when they are sleeping) teleport to their location and kill them / take their stuff. Good characters might rely on this only to take out the BBEG, while Evil characters (or characters that have recently undergone an alignment shift) have little reason not to do this as often as possible. There are defenses against this technique, but to have every target constantly have those defenses going all the time stretches the veil of disbelief beyond its natural limits.
Splat Prestige - Custom, wacky character builds are fine and are part of the game. Every PC in the party having a minimum of 6 classes (many prestige classes) by level 20, though, can result in such anti-climatic encounters as no less than 21000 points of damage to Kyuss in the first round.
I'm not saying that a simple Rule 0 won't eradicate these issues, I'm just saying that they've ended games in my past. What has ended your games in the past?