Wall Banger/Tabletop Games

Card Games

 * Magic: The Gathering has some fun ones. First, we have that artifacts originally were turned "off" when tapped (turned 90 degrees). Fine. Except that they changed it, and now they specifically rewrote Winter Orb to include the broken "turned off when tapped" factor. Then there's the Humility (all creatures are vanilla 0/1s)/Opalescence (all enchantments are creatures) rules clusterfuck, and both were Standard-legal at the same time. There used to be a card type called Interrupt, associated with damage prevention (Reverse Damage), counterspells (the eponymous card), and mana generation (Dark Ritual). Interrupts were an exception to the FIFO rule. In Fifth Edition, they changed the rule to LIFO, but kept the Interrupt type, until Sixth Edition. By the way, Sixth Edition experimented with the idea of damage on "the stack". This meant that my Shock Troops could do damage, then I could sacrifice them for more damage. And that's to say nothing of the arbitrary times they put reminder text on a card, usually defeating the purpose of giving an ability a name.
 * Damage on stack has been taken out in M10.
 * In one of the webcomics, the Planeswalker Koth needs to convince another Planeswalker, Venser, to travel to Mirrodin with him. When diplomacy breaks down, he improvises; he fuses Venser's helmet into one solid mass over his face and threatens to leave him that way unless he complies with Koth's demands, which he does. The problem? Venser is a wizard specializing in teleportation. There was quite literally nothing stopping him from teleporting himself out of the helmet or teleporting the helmet off of his head, unless he wanted to see Mirrodin again anyway - and the quickest way to do that was not to antagonize the jerk who redesigned his helmet.
 * Mitos y Leyendas, a Chilean card game that used to be fairly popular, pitted, as it's name says, creatures and heroes from different mythologies against each other, and, of course, the gods occupied the top tiers among each deck. Until the "Heroes" set, made to celebrate the country's bicentennial. Since it was based on the War of the Pacific, there wasn't too much to draw inspiration from, which lead to the wallbanger in question: They used the important historical figures as top tier cards. This, in other games, wouldn't be too bad, but here it brought Badass Normal to idiotic levels. Arturo Prat, a ship captain who performed a (pretty impressive, but still) Last Stand, could stand toe-to-toe against Zeus and Thor, and people who were otherwise colonels and lieutenants could curbstomp manticores and giants. I know it's not exactly bad to be proud of your heritage, but this is Author Appeal in a very bad sense. The company that made the cards folded shortly after, but not without producing the "Trincheras" set, based on World War I, which had even bigger problems.

Tabletop RPG

 * While there are many points of dissension among the Exalted fanbase, it is universally agreed that the crunchy bits of Scroll of Heroes, Scroll of the Monk, and most of the Charms in Dreams of the First Age were abysmally written. For stuff that was actively hated rather than just really bad, however, there was the Locust War chapter in first edition Autochthonians, which was an adventure module written without considering the involvement of player characters (which is dumb enough in a generic game, but this is Exalted - player characters can reshape the world if they try hard enough), relied mainly on the device of "NPC's do things, the players...um...bear witness to their badassery, I guess", and had nonsense like a culture that has never seen an ocean being able to throw down in naval combat with the premiere oceanic power in the world and win.