From Hard Drop - Tetris Wiki
Tetris is an abstract game with some elements of luck and a range of goals depending on the variant, making it difficult to formulate definite strategies and tactics. In many variants, a player's success lies in how accurately, efficiently, and quickly he or she can perform. This remains especially true for matches against an opponent. Some variants remove the time element, making speed less important.
Some techniques are common among many experts. Remember that beginner players will naturally take the route easiest to learn, which may not always be the best. In some cases, a player may need more than just one sitting to learn how to do something a different way. An important trait of a successful player is that he is able to change his ways and take the time to learn something better.
Note that while the name of this article is "General technique", the following list of strategies in its current state has a bias to games that conform to the Tetris Guideline. Other games may have different rules, rewards and features which all call for different favorable strategies. What may be considered foolish actions in one game may be essential strategies in another, and vice versa.
- Stacking for tetrises. Almost all games, except those early games licensed through Andromeda and Mirrorsoft, reward the player for clearing more lines at once. In most cases, clearing a single in order to move on to the next tetris is more efficient than building the single up to a double or triple. Although, in games with line clear delay, it is of course faster to clear one triple rather than clearing three singles to get to that upcoming tetris.
- Clearing garbage. In a match against another player, the goal is to prevent yourself from topping out and to make your opponent top out instead. Remember to look down and see what garbage you have to deal with. In a lot of cases, it is more beneficial remove this garbage than trying to send more to your opponent.
- Piece preview. Keep an eye on the next piece(s). They will help you prepare for how you should place the piece at hand.
- Stack evenly. When garbage comes, you want to stay as close to the bottom as possible. Don't stack perfectly even, though. You want to be able to deal with Zs and Ss.
- Soft drop sparingly. In games where hard drop is fast, soft drop is slow or unavailable, and firm drop is not available, avoid situations where you must slide. If a situation occurs where it is necessary, for example the first two tetrominoes are S and Z, try to stack so that you only need to soft drop and slide once instead of twice, or use a platform opening. With respect to T-spins, you'll need to soft drop.
- Practice often and effectively. The best way to improve your ability is to practise often and to practise playing how you would like to play ideally. Push yourself!
 Techniques for Guideline games
Newer Tetris brand games follow the Tetris Guideline. For these, the following additional techniques apply:
- Dual rotation. Rotate both clockwise and anticlockwise, and when moving left and having to rotate I, S, and Z, use anticlockwise-- inverse for right. The tetromino will need to move once less.
- Open column preference. If you leave a side open for tetrises, use the right side. If you leave the middle open for tetrises, use the right-middle. Since non-I and O tetrominoes spawn closer to the left, and the symmetrical I will be the only piece needing to go in the open column, placing the open column to the right will require the non-I and O tetrominoes to move less.
- Smart holding. Don't excessively hold tetrominoes. Although holding is preferable to soft dropping, do it only when necessary. Hold I tetrominoes, but if the first tetrominoes come I then Z, don't hold the I. This will require a soft drop. If you have four rows lined up for a tetris, don't hold the I. Use it unless some other reason justifies using a frame to hold it. If you get a tetromino that will result in a soft drop later, hold it, but next time stack better. Really, even experts hold a lot, but it's important when starting out not just to use it because you don't feel like thinking about how to place a piece. Learning to stack efficiently in these difficult situations where you don't immediately see somewhere that fits is very important.
 See Also
- Tetris Stacking - General guideline to stack consecutive tetrises
- Multiplayer Techniques - Various multiplayer tactics
- Movement Finesse - A system to place tetrominoes with the least amount of keypresses