50/60Hz and the improbable chance of a good time in SMK

[duffjr]

The time trials site of Super Mario Kart http://www.geocities.com/smkplayerssite is one of the most active sites for classic gaming competition. On one particular course, Ghost Valley 1, there is a shortcut over a small gap after the 3rd turn. The gap is measured to be eight sprites long using Track Designer 1.11 by bouche. In 60Hz, the speed is about 2.5% faster than that of 50Hz, so the jump is slightly easier to make without boosting. The maximum distance one can jump at top speed is about 8-8.25 sprites, slightly less on 50Hz because of the lower top speed. When the back of the character's kart is more than 50% on one sprite, that character rests on that sprite. So, the jump must be made before the kart passes over 50% of the last floorboard sprite before the gap. Unfortunately, the jump over the gap cannot be made everytime on either system, supposedly because there are only 50/60 frames per second and the kart travels about 30 sprites per second or one sprite every .03 seconds, 1-2 frames. Basically, your success on the jump depends randomly on what portion of the sprite you will be at when the frame is rendered near 50% of the last sprite before the gap. Therefore, few have recorded successful jumps on all 5 laps in 60Hz, and two have achieved 3/5 successful jumps in one race on 50Hz.

Can anyone think of any other games where the randomness of the frame vs. character's position determines your success rate? Or can anyone provide a more in depth explanation?

[michael flatley]

I'd say all games have something like this. If you start performing frame-perfect tricks odd things will start to happen. I've come across tricks in Super Metroid that I'd call random. To be honest every game I've played I've found some way to mess with the physics and pull off something not intended by the programmer. Quake 3 is my favorite game because you can exploit the game physics a million different ways. For instance if you fall from one platform to another and the distance is just right you can bounce back up or gain an insane amount of horizontal speed.

I wasn't aware of the example you provided from Mario Kart, though.

[kieran_]

Edit:
Never mind. I was wrong.