The classic tetris scene has been crazy lately. Rolling (the name of the new strategy) allows players to easily play past the "kill"screen of level 29. Classic tetris matches are becoming endurance matches and we're seeing new records broken left and right of highest score and highest level in both PAL and NTSC versions. For Classic Tetris World Championships they're considering adding a second killscreen by editing the rom to limit the length of matches.
CTWC is yearly, and is neat, but most of the community and talent is developed at the monthy tournaments called Classic Tetris Monthly. The guy in charge, Vandweller, doesn't get nearly the credit he deserves for fostering the communtiy. If you're curious, here is the twitch. https://m.twitch.tv/monthlytetris They also upload to YouTube under the same name.
CTM is where rolling was first demonstrated. Eric getting to glitched colours happened during CTM. They also had a level 49 line cap (now 39) prior to CTWC this year because they had a full 10 months of tournaments showing the necessity for it. CTWC did not heed their experience, unfortunately. Also the past three champions are frequent winners of CTM. Except Joseph, who used to be a big part of the scene, but he's off to try other things.
Anyways, I recommend CTM over CTWC as a starting point if you're reading this and are curious.
NTSC being 60Hz and PAL being 50Hz, there is compensation implemented in code such as shorter autorepeat delay (16 to 12 frames) and rate (6 to 4 frames), as well as gravity drop speed past level 10 (-1 frame) to keep the gameplay sort of similar to casual players.
But then details matter at these insane player levels, NTSC is 1 row every 2 frames on levels 19 to 28 then 1 frame starting with 29, but PAL is 1 row every 1 frame ever since 19, so given that frames are not the same duration PAL is comparatively harder than NTSC starting with 19 but easier starting with 29 (... provided one can survive up to that).
So wall-clock PAL gravity ends up being 1.25x faster than NTSC (but with quicker DAS: 1.5x faster delay, 1.33x faster movement), then at 19+ is 1.67x faster, then at 29+ 0.8x "faster".
Just FYI, PAL and NTSC are field based, not frame based. PAL is 50 fields per second, and NTSC is 60; a field is either the odd or even lines of the display. So that's 525i/50 or 480i/60
The NES always sends the shorter type of fields, so for NTSC you actually get a little over 60fps with the same 240 lines every fields; it's not standard NTSC timings, it's 240p60; same deal with PAL. The SNES and Genesis could optionally output interlaced video, but only a handful of games did.
No. The killscreen was 29. They couldn't go past it. With rolling they can potentially go much further. To limit the length of games they decided to stop at level 49. Then recently the official kill screen decreased to 39. Any points after level 39 does not count.
Fans and players generally prefer having a lower killscreen, while keeping a high level of gameplay.
https://www.youtube.com/watch?v=9hcZ1tNwvlc https://www.youtube.com/watch?v=l2r0fIQ3RI4