This achievement requires earning three badges. One is a grind. One is very difficult.Show-off: Clear 100,000 lines in online mode
There are literally zero random online games going on at any point in time so you'll have to find someone to boost this with. You're looking at about 75 hours of online play depending on how fast you can go. Note that your total lines are tracked, but lines earned in online play are not, so be sure to keep track yourself so you know how far along you are.T-spinner: Complete 3,000 T-spins
If you make it a point to get a t-spin when the chance arises, this should come well before you clear 100k lines for Show-off. Note that you don't need to clear a line for a t-spin to count, but you do need the "t-spin" notification to come up on the screen.Simply the Best: Do a 20 combo
This is tough. Really tough. You need to fill the well in such a way so that you can drop 21 consecutive pieces and have each one clear a single line. You'll clear 21 lines in this process, with the combo starting on the second cleared line. I've included two examples. The first, which I found on YouTube, is done flawlessly from the start and required an absurd amount of luck to get the exact pieces needed to build the well perfectly. The second is my run where I fumbled for a while to get things set up properly (which I edited out- boring), then completed the combo.
After completing the third badge, the achievement should
pop. It didn't for me initially- it took three weeks until it magically appeared on my profile.