I was really hoping the 6x combo would come back in the PC game in some form. It's the only way that you can save a 5x tower from breaking through the roof through skill rather than luck. That's the one downside of the game: literally any time you can get the 4350 points from a 5x tower, there is a 1/6 chance of immediately breaking through the roof, even if you break the tower immediately. As a result, most of my high scores come from games where, by pure chance, I got a lot of 5x towers without a block immediately landing on top. It would be nice if, even if difficult, there was some way to get the full 5x bonus without exposing yourself to a 1/6 chance of a crippling dead block. Getting 5x towers quickly is really the only way to get a high score.
I previously tried strategies destroying every tower before it gets high enough to reach the ceiling, but since it takes more than two 4x towers to equal one 5x tower, it takes way too long. Even playing a 10 or 20 minute game like that, you don't reach 60k. Even worse, a 4x tower has a 1/36 chance of automatically breaking the roof, and you need more of them, so you end up facing the same risks.