Unexpected unbalancing/disruption...

[Johnny1A.2]

Just out of curiosity, what have GMs allowed a PC to have, do, or otherwise use that looked reasonable and not a problem, but turned out to be wildly unbalancing or disruptive to a game? I mean a skill, advantage, or possession that looked completely in-genre, in game, point-balanced, whatever, but somehow turned the game inside out?

That is, not invulnerable to bullets or twenty levels of Multimillionaire, but something that seemed natural and reasonable and ordinary in terms of the campaign, but which blew it up, or came close to it?

[Donny Brook]

I've seen Trickster derail a campaign quite badly.

Wild Talent (spells) with Retention turns a mage into a narrative-crushing Swiss army knife.

[PTTG]

Super jump 15.

Jump from ground to helicopter in 3 seconds and always land safely.

Helicopters were exploding left right and center.

[Dustin]

Magic has its pitfalls in this regard. The Concussion spell (M26) had to be nerfed in my games, and recently I found that alchemical Sleep pastilles (M218) were alarmingly potent, to the point of becoming an "I win" button against anything not immune.

Fetching & Carrying potions (M214) allow those who can afford them to basically ignore Encumbrance for 1d+1 hours, which is making them rather more prominent in my game than I anticipated, for heavy fighters to truck around with unpenalized Move and Dodge scores despite serious armor.

[Mailanka]

I thought it would be cool to have some high-level heroes rebuilding a post-apocalyptic society (TL 9) in a zombie-infested world. The zombies were the primary (but far from only) threat.

One player was a robot, which is pretty reasonable... only none of the zombies could hurt him. Setting aside his immunity to metabolic hazards, they couldn't even scratch him, because he had ~20 DR. It wasn't much, but it completely drained all the tension for him out of all zombie fights, and because of this, he just front-lined all of the zombie fights and unless I did some crazy shenanigans (that got tiresome if I used them again and again) the zombies dropped from "potential problem" to "logistical nuisance."

That largely wasn't a very successful game (though I just had a player, not the robot, talking about how great it was. Different perspectives, I suppose).

[Wavefunction]

Not actually a GURPS unbalancement, but in a Pathfinder game I played a monk (who are pretty damn fast) with boots of speed (doubling his speed), then acquired an artefact that allowed me to boost my speed further, and long story short, and flying kicked the big bad in the head at 154 miles per hour.

[malloyd]

Originally Posted by Wavefunction

Not actually a GURPS unbalancement, but in a Pathfinder game I played a monk (who are pretty damn fast) with boots of speed (doubling his speed), then acquired an artefact that allowed me to boost my speed further, and long story short, and flying kicked the big bad in the head at 154 miles per hour.

Yeah, it's those combinations that sneak up on you, the ones where any one element is reasonable, at least for the character you *planned* it for, but several of them get combined, or some other player uses the precedent to claim the same trait for a character you didn't plan it for, and suddenly....

For GURPS I suspect the ones that are the most troublesome are DR (the line between good but reasonable DR and effectively invulnerable is not huge, maybe no more than 3 points. Well within the range that something that provides a completely reasonable boost to an unarmored character can push the heavily armored guy over the top if he gets to borrow the item or invoke the same rule) and stuff that reduces the energy cost of spells, until suddenly something you didn't think about goes *free* and starts getting cast at the slightest excuse.

[oneofmanynameless]

Originally Posted by malloyd

For GURPS I suspect the ones that are the most troublesome are DR (the line between good but reasonable DR and effectively invulnerable is not huge, maybe no more than 3 points. Well within the range that something that provides a completely reasonable boost to an unarmored character can push the heavily armored guy over the top if he gets to borrow the item or invoke the same rule) and stuff that reduces the energy cost of spells, until suddenly something you didn't think about goes *free* and starts getting cast at the slightest excuse.

I agree. Even DR values that seem totally reasonable because "ordinary" equipment can grant them at that TL level can totally unbalance and ruin a games feel if not watched out for.

The flip side of that is that a wide variance in damage outputs can also be very difficult to balance if you're trying to keep everyone feeling useful in a fight. It's difficult to balance enemies that can be hurt by someone who only deals 2d damage but won't be obliterated by someone with a fully auto Beowulf .50 assault rifle. On this front, something I've found is that no amount of injury tolerance is enough to stop a .50 caliber machine gun of any variety from obliterating a target faster than any muscle powered weapon possibly could, which makes games where you want swords and guns to exist side by side very very difficult.

Originally Posted by Donny Brook

Wild Talent (spells) with Retention turns a mage into a narrative-crushing Swiss army knife.

I've never played a game where basic magic didn't feel either incredibly single-purpose or the mage was just able to solve every problem.