When a unique mechanic becomes too much.
I am a huge fan of interesting mechanics in role playing games. Drawing playing cards to make my character in Deadlands: Hell on Earth? Yes, please. It beats rolling dice. Will my character do crazy stunts just to get Hero Points? Of course.
The problem I'm running into is when the unique features of the game get in the way of the game itself: the ridiculous amount of dice you roll in Exalted that takes forever to figure out the amount of damage you do, the ten thousand D&D feats that stack, and, the one that sparked this post, the stupid amount of charts in Hackmaster.
Our group has been playing in Hackmaster for a couple of months now, at our GMs request so we can do the Temple of Existential Evil. That's all fine and good, it allows us a breather from our regular characters. It's also given us new appreciation for how epic our characters are because we are all level 4-ish in Hackmaster. We've had a few weeks where we couldn't play and then it's taken us a hot minute to remember how to play our characters.
But the charts are out of control. It's gotten to the point where I cross my fingers no one crits during combat because it means that everything grinds to a halt as we pull out the crit chart and roll a crap ton more dice before we can move on in initiative.
And don't get me started on moving during combat and the fact that it ups your place in initiative. Or the fact that the same target can have two wildly different target numbers to hit depending on what class is attacking.
It's too much. And has sucked all the fun out of a throw away part of the game that our characters got sucked into. To the point of my character has broken with her cautious behavior and is forging forward with no care for her safety just so we can get this portion of the game over with and get back into our bodies.
All of this to say, if you are making a game and have an interesting mechanic that you want to use, playtest the hell out of it. Is it actually fun or does it slow the game down to unplayability? Max out the possibilities to see how broken it can get and see if it is truly needed or how you can fix it.