The key to getting big scores in Dots is a trick that you won't find in the app description or in the game: make squares. When you connect dots in the shape of a square it removes all of the dots of the same color and replaces the board with dots that are also not that color. In other words, making squares actually makes it easier to make more squares by removing colors from the board and giving you a higher concentration of the colors that are left over. I have to admit this little trick was lost on me when I initially wrote this review and it changes my view of the game entirely. Making squares becomes the primary mission in the game, so you'll constantly be scanning the board to set up squares.
As you complete games, the dots you have collected can be used to purchase one of three superpowers. A Time Stop stops the clock for 5 seconds so you can add on to your score. The Shrinker lets you double-tap a dot to make it disappear, so -- with some planning -- you can set up squares by removing a dot that's in your way. The Expander is the most powerful of the three (and the most expensive at 5,000 dots), letting you choose one dot to remove all the dots of that color from the board. You can use the Expander and Time Stop super powers only once per round, but the Shrinker can be used as much as you want.
The ability to make squares for more points makes the game exciting as you desperately try to line dots up into squares, but I still think it needs something more. I think Dots could really benefit from some sort of bonus for connecting large numbers of dots in one move. As it is, you score exactly as many points as the number of dots you connect in a line so even if you get 6 dots in a row, you'll still only score 6 points. In other words, maybe some sort of reward for going after the big chains would make it even more exciting.
Dots would also benefit from more game modes. The core game is very addictive, but with a little more variation I think it would keep the game interesting even longer.