I want to add some new categories but I dont know the type of categories that you guys like most. So if you want to help me out I would be happy. Please post your ideas with this layout:
Category name:
Rules of the category:
Description(optional):

Thank you in advance

I was thinking of a category like KO% or Kill% in both Tetris 99 and CPU Battle modes.
Name: KO%-Kill%
Rules: Do a KO as fast as possible. Time starts at GO. Time stops when the KO sound plays.
Description: This rules are general I will make specific rules for both modes.
Let me know if you agree

Yeah you could make this like 1-Kill, 5-Kills, 10-Kills... up to idk 30 Kills maybe, but I dont know if this is to much, cuz kills are also very luckbased

One of the most "run" category in tetris in general is the 40lines-challange. The DLC has 150 and 999 lines timer and we could add 40 lines - ofc we would have to stop the timer by ourself but I think thats not a problem. So 40 lines would be an idea to 150 and 999 lines challenge. Rules like 150 and 999 ofc. (You have to start a 150-Lines-DLC-Challange-Game and then do 40 lines instead of 150)

Something like "do 10 tetris as fast as possible" would be cool too, but we have to count the tetrises and thats ugly I guess - also for the ppl who have to verify the runs.

I will think about this and maybe I will get some ideas of more usefull categories.

These are my suggestions and only suggestions for the moment. You can modify it if you like or ignore some (or all) of them
Maybe I will add some more. Let me here what you think about it please. Thank you.

--
Topic:
Marathon
Category name:
40 Lines
Rules of the category:
Same as 150 Lines
Description(optional):
Start 150 Lines Game and do 40 Lines as fast as possible
(As I wrote already. There is no IGT for 40 lines so we have to stop at the
40th line)

--
Topic:
Marathon
Category name:
500 Lines
Rules of the category:
Same as 999 Lines
Description(optional):
Start 999 Lines Game and do 500 Lines as fast as possible
(This is only to find a middle thing between 150 and 999, cuz 999 lines
will take a lot of time. There is no IGT so we have to stop at the
500th line like for 40)

--

Topic:
Challange
Category name:
10 Tetris
Rules of the category:
Start a normal game against other people (no DLC)*.

Time starts when the screen shows "GO" on a new game.

Do 10 Tetris as fast as possible.

You have to show the statistic page at the end of the game.
Time stops if 10 Tetris (or more) are shown on statistic page.
Place doesn't matter at all.

Runs must require video proof.

Emulators are banned.
Description(optional):

--
Topic:
Challange
Category name:
10 double T-Spins
Rules of the category:
Start a normal game against other people (no DLC)*.

Time starts when the screen shows "GO" on a new game.

Do 10 double T-Spins as fast as possible.

You have to show the statistic page at the end of the game.
Time stops if 10 double T-Spins (or more) are shown on statistic page.
Place doesn't matter at all.

Runs must require video proof.

Emulators are banned.

--
Topic:
Challange
Category name:
10 triple T-Spins
Rules of the category:
Start a normal game against other people (no DLC)*.

Time starts when the screen shows "GO" on a new game.

Do 10 triple T-Spins as fast as possible.

You have to show the statistic page at the end of the game.
Time stops if 10 triple T-Spins (or more) are shown on statistic page.
Place doesn't matter at all.

Runs must require video proof.

Emulators are banned.

*we can do these three categories (10 Tetris, double T-Spins and triple T-Spins)
also in 150 Lines DLC mode to neutralzie luck. No opponents and no garbage
means no luck factor. So we can do it on normal games AND DLC if you want to.
(I dont mean against CPU opponents, I really mean in the 150-lines-single-player-
mode, to have no opponents)

--
Topic:
Challange
Category name:
No garbage
Rules of the category:
Time starts when the screen shows "GO" on a new game.

Play as long as you can without getting garbage from other players.

Time stops if you can't defeat your first garabge line or if
you win the game without any garbage.
(Bigger time better than small time on this category!)

Runs must require video proof.

Emulators are banned.

(I think its kinda cool, but I dont know, cuz mods have to look very closly to the run if
there is any garbage..)

As I said I would like to help you guys as a mod if you want to

I mean sure, but called it T-Spin Double instead of Double T-Spin etc.

For now I added the 40 lines challange to 150 and 999 marathon mode. What do the others think about the suggestions? Anything else?

I saw that the daily missions are looping. This may sound stupid, but what if there is a category for completing them as fast as possible from the boot of the game to the end.

We can probably set two subcategories.
Two missions and four missions.
The two missions category is only available for those who haven't the big block dlc and the four missions category is for those who have the DLC. Time starts at game startup when it shows the missions list. Time ends when the last mission is completed. Is this ok?

This would be one way to add this as a category. The only problem would be that some missions are just faster than others, so you wouldn't have a chance to PB/WR on some days.
The other way would be to set this as Level Categorys and every day would be a level.
There shouldn't be to many levels, because the missions are looping qickly, but I don't know if this is in the same mission-combinations.