The Worst Game Mechanic friends have all gathered to play a game.  There are five of you, but the game is only 4 players.  Someone has to sit out, and it’s randomly decided that that’s you.  Ever had that feeling? It’s a sinking frustration, because you can’t really blame anyone but the randomness that chose you, and the game that put you there.  So you feel helplessness, and all alone.

Fortunately, this doesn’t actually happen because your friends aren’t that apathetic (hopefully!). They’d instead choose to play another game, because they don’t want one of their friends to not play.  So why then, do so many games have mechanics that do exactly that: have people not play the game?!  The worst game mechanic in the world is any which causes a player of the game to do exactly the opposite of what a game design should strive for: having fun by playing the game.

The most simple example of this is the lose a turn mechanic.  The affected player has to sit out for a round while everyone else plays past them. That’s not at all fun!  Likewise, take an extra turn is almost as bad.  This is essentially forcing everyone but one player to lose a turn.  This is almost obvious, yet game after game include it as an effect of some card, some ability, or some reward.

This gets me to the important part for RPG mechanics:

Never give a player more "actions" than another in any given "round".

Period.  I don’t care about attack speeds, injuries, or status effects.  This problem can be much more subtle: an extra attack here, a bonus action there, a loss of your movement action.  An extra re-roll.  Any mechanics that lets one player play more than the other players means that one player is hogging the spotlight.  They are taking up more of everyone’s time than any other player.  Even if a wizard’s fireball blows up the entire room, the fighter with ten attacks will be rolling for minutes, while the wizard sits back and waits for the next day to roll around (don’t even get me started on ‘encounter’ or ‘daily’ powers…).  Equally cool in terms of fiction, and even balanced in terms of power. But the bottom line is that the wizard just doesn’t get to play as much as the fighter.

Major edit after a lot of people have commented on this:
This is not a major issue, if an issue at all, in most role playing games.  Extra actions can be a lot of fun - for those who get them.  But it rarely impacts the other players.  In fact, the ‘human factor’ is a much larger contributor to players waiting around than a player’s extra actions ever are.  But these arguments don’t disprove that such mechanics have a core problem.  For science, you really have to focus in and look at things individually as well as within the big picture.  Narrowed down, these mechanics have the potential to lag a game down.  In the big picture, it’s only a ‘real problem’ when one or more factors are also put on top of it: such as that one guy who takes forever to decide what he’s going to do.  The issue is multiplied if that guys is also the one that has multiple actions.

The idea behind the spotlight being equal per ‘round’ could in fact be drawn out over multiple sessions.  I’m perfectly okay with games that shift major spotlights game to game, especially when it’s story/fiction based.  But that’s not one of these mechanics that I’m talking about.  The problem is that a mechanic such as ‘lose a turn’ could completely destroy someone’s spotlight day (e.g. they get turned to stone by a Medusa), now wasting multiple game sessions for that player, rather than just one or so rounds of a combat.

The bottom line is that these types of mechanics prevent player engagement, and that’s why they are not “good”.

End Edit

Next up is stuns.  My friends and I have a saying:  “Stuns win games”.  If you’ve ever played a MOBA like DoTA, LoL, or HoN, you know how true this is.  But it’s equally true for every other game genre as well.  When someone cannot act, cannot play the game, the other players have a 100% pure advantage.  Sure, this can be balanced (e.g. the cost of the stun is high enough to offset the time lost), but the key here is that it is not fun.  The player that is stunned gets aggravated, increased in direct relation to how long they are stunned for.  Steer clear of these mechanics, and balance your game in other ways.  For example, don’t have “ice” stun - make it “slow”.  Detriments are interesting; you have to play around them, usually calling for a change in strategy.  But you’re still playing.

In RPGs (and other co-op games), an important thing to remember is that when players are not against other players (e.g. a GM, cards, or computer AI), these types of mechanics are okay for the players to inflict on their enemies, because enemies aren’t there to have fun.  It’s not about them, it’s about the players.  So have your mage freeze that dragon; just don’t let the rogue sprint, jump, attack, backflip, and attack again all in the same go.

Stuns Win Games - OPifex Gaming

Mechanics that force you to not play the game you sat down to play are the worst mechanics in game design.  And there are plenty of shitty, broken, unbalanced, disruptive, un-intuitive, complex, confusing, nonsensical mechanics out there.  There are things that just don’t work.  But none can top the mechanics that do exactly what they’re intended to do: stop people from playing.

Another major edit, for more examples:
Companions/pets give players complete extra turns. They are doing more per turn than other characters, and I’ve seen plenty of games bog down to a crawl because of it.  This is generally why we don’t give the same person multiple characters to play within an RPG, unless everyone also gets multiple characters.  It’s hard for players to control that much - i.e. it takes too long in comparison to everyone else.

Magic: The Gathering has “take an extra turn” cards that, when stacked, can make opponents walk away from the table, because they don’t want to sit and watch someone play solitaire cards for 10 minutes.

Dominion is a game where “extra actions” per turn is a core part of getting players’ engines going.  But the key to dominion is that everyone starts with an equal opportunity to gain these extra actions.  The game is about that, but is not the major selling point of the game.  I’d argue that strategies that get more actions are more ‘fun’ to play in dominion, but that doesn’t stop other strategies from also being viable/fun, because the game centers around figuring out the ‘optimal’ card strategy, not necessarily the turn-by-turn play.  Arguable - I know - and I’d then start to argue that the extra actions make some strategies more enjoyable than others, which isn’t good game design.

Lastly, my favorite example from people’s comments: there’s an obvious line between a barbarian having a couple of extra swings with his axe and the druid who summons 8 great owls to control for the next six turns. The point - when it comes down to it - is to be careful with your game designs.  These types of mechanics are awesome for the player, but generally not so much for the other players.