BlockBot v1.3

Plays Block Blast! for you on your Windows PC. It watches the screen and drags the pieces with the mouse.

Install Google Play Games for PC: play.google.com/googleplaygames, sign in.
In it, search Block Blast, install, and open it. Start a Classic game.
Open BlockBot.exe. If Windows says "Windows protected your PC", click More info then Run anyway. If your antivirus blocks or deletes it, that's because it's a new program that moves the mouse and isn't signed: choose Allow / restore it from quarantine.
Press F8 (or the Start button). Press F8 or Esc again to stop. Pushing the mouse into a screen corner also stops it.

It can't find the game: click Select game area and drag a box around the game.
v1.3: it measures exactly where the game draws the piece it's holding, lines it up, holds still, then lets go. If it can't line it up it puts the piece back. It moves its own window off the game by itself.
Pieces land in the wrong spot: click Reset drag, then F8 again.
Pieces don't move at all: switch Input to Window messages.
Popups, ads, the "Game over" or "new best" screen, or the game being minimized: it pauses and keeps going by itself when the board is back. Moving the mouse yourself stops it.
Still stuck: it shows a yellow note with an Open log folder button. Send Tab the file log.txt from that folder (the Send log to Tab button opens it too).
Drops miss when it's fast: switch Speed to Normal.
Answer only mode doesn't touch the mouse: press F8 and it shows the best moves (1, 2, 3) in its little window.

Settings and a log are in %APPDATA%\BlockBot.