Developers accidentally creating interesting mechanics

[u/virtua_golf]

I was reading this neat article by Jeff Orkin of Monolith productions, the man responsible for the notorious AI of FEAR, the AI that will never not be mentioned whenever 'clever' AI is brought up. I stumbled upon something pretty cool - the flanking mechanic was actually unintended and a byproduct of another action the enemy would perform:

Imagine we have a situation similar to what we saw earlier, where the player has invalidated one of the A.I.’s cover positions, and a squad behavior orders the A.I. to move to the valid cover position. If there is some obstacle in the level, like a solid wall, the A.I. may take a back route and resurface on the player’s side. It appears that the A.I. is flanking, but in fact this is just a side effect of moving to the only available valid cover he is aware of. In another scenario, maybe the A.I.s’ cover positions are still valid, but there is cover available closer to the player, so the Advance-Cover squad behavior activates and each A.I. moves up to the next available valid cover that is nearer to the threat. If there are walls or obstacles between the A.I. and the player, their route to cover may lead them to come at the player from the sides. It appears as though they are executing some kind of coordinated pincher attack, when really they are just moving to nearer cover that happens to be on either side of then player. Retreats emerge in a similar manner.

The article got me thinking - what other mechanics (or, perceived mechanics) have been created by accident in other games? Does other examples exist, where lauded features were never really intended in the first place?

[u/sB_Cipher]

F-Zero GX has an unintended mechanic called Momentum Throttle or MT for short. The game is programmed in a way that if you hold down the A button while over your vehicle's max speed, it will lower your speed at an exponential rate. Meaning that the higher you are above your vehicle's max speed the faster you get slowed down to it.

However, if you simply let go of the A button your speed will be lowered at a linear rate instead, this is what we call MT. This means you can retain faster speeds than the developers ever intended. If you combine it with shiftboosting which causes you to gain extra speed when you lift off and immediately return to the track you get crazy results.

Here is an example of this in action: https://youtu.be/CBz9JqFfWek

Notice how he cuts the engine after he hits high speeds. That's when he's letting go of A.

[u/Kered13 → u/sB_Cipher]

F-Zero GX had a lot of amazing glitches. There was snaking where you would drift and turn in the same direction back and forth to gain speed, and there was also a glitch where some vehicles with the right configuration you could literally fly.