Tetris Splash
12 Achievements
200
15-20h
Xbox 360
Clear 5 Lines
Clear five or more lines during one Single Player or Online Multiplayer game.
10
How to unlock the Clear 5 Lines achievement in Tetris Splash - Definitive Guide
This you will get within the first minute of gameplay (even less if you're already a pro at tetris). Just simply clear 5 lines by having blocks lined up horizontally untill they clear off the screen. You can do one line at a time, a tetris and clear one line, or any combo of clearing lines. You can even make a combo out of it by clearing one line with each new block you get.
You should be able to get this easily by playing the game. All achievements unlock at the end of the game, in the game review screen.