A new row of letters pushes up from the bottom: every 20 seconds on Easy, 10 on Medium and 5 on Hard.
Spell words of 3+ letters. Start on the bottom row, then move up, diagonally up, left or right to touching blocks — never down.
Tap letters one by one, or drag through them. Hit Blast! (or Enter) to explode the word. On a keyboard you can just type it.
Blocks above the gap fall down to fill it.
Watch out for Block Fill (fills in a hole) and Block Flood (fills every hole in the tower).
Bomb goes off when you clear a block touching it, blowing up every block around it.
Clear a block touching a Magic star to make a wish: tap any letter in the tower to highlight every block with that letter, then hit Blast! to wipe them all out.
Rare letters score more. Longer words multiply your score.