A train of colored marbles snakes toward the drain. Fire matching marbles into the line to pop 3+ in a row before the front reaches the end.
A turret sits below the path. Drag anywhere on the screen to aim it — a guide line shows the shot direction. Release your finger to fire the marble currently loaded in the turret.
The fired marble flies straight and inserts into the train wherever it touches. If your insertion creates a contiguous run of 3+ same-color marbles, those pop and the marbles behind the gap snap forward to close it. Cascading pops (a closing gap creating another 3+) chain — bonus score for each chain link.
The whole train is constantly marching forward toward the drain at the end of the path. If the leading marble reaches the drain, the game ends.
Clear all marbles in a wave to advance: +50 bonus, next wave starts with a longer train, faster march, and possibly more colors. Score = marbles popped + chain bonuses + wave bonuses.
Plan around the NEXT marble, not the current one. A small indicator beside the turret shows the next color to fire. If you shoot the current color into a quick easy 3-pop but the next color has no good shot, you've wasted the turn — sometimes it's better to shoot the current marble into a SAFE spot just to swap it out and get the next better-positioned color into the gun.
Match into runs of 2, not lone marbles. Inserting your marble next to a pair of the same color creates an instant 3-pop. Hunt for pairs in the train and target the gap next to them. A lone match (1+1+1=3) is harder to set up than a 2+1=3 hit.
Watch for chain setups. If you see a row like RED-BLUE-RED-RED-BLUE and you can pop the two reds in the middle, the cascade joins BLUE-BLUE and you've earned a free combo. These are the high-score plays — slow down and look for them.
Don't shoot too often. The train is constantly advancing — you can't undo a shot. Wasted shots that miss the train or create no progress just consume time during which the train marches forward. When in doubt, wait a second and let the train shift; a better insertion angle often appears.