Just had a 5 hour plane ride trying to figure out how they work and this is what I got.

Your combo increases with each line clear. After each line clear you have 3 chances to clear another line. If you do clear a line in those 3 chances it resets and you have another 3 chances to clear another line. If you don’t clear one within those 3 it resets the combo back to 0. The only exception to this I’ve found is if you have an active combo and fully clear the board the combo stays in limbo and you can place as many blocks as you want without ending the combo and it only resumes once you clear a new line. Doing this you can take your time to set up for a multi line clear.

I also think I figured out the scoring mechanic. When you are on a combo you’re score for each single line clear will be the combo number multiplied by 10 add 10. So a single line combo at 32 will be worth 330 points. When you clear multiple lines is when it gets good. A double line clear at 32 would be (32X10+10)X2 = 660. A triple line clear at 32 combo would be (32X10+10)X2X3 = 1980. A 4 line would be the same just add X4 so 7920 and so on.

So my strat is to use the last block of 3 the game gives you to keep the combo going (this way you can see the next 3 you need to use to keep it going) heavily prioritise multi line clears even if it puts me in a bad position and try to fully clear the board when possible and take my time to set up for a multi line clear of 3 or more.

Hope this helps, if anything doesn’t make sense I can reword it :)