The blocks with the letters on them, as seen in the image below, is what're unique to TetriNET. These are known as "special" blocks; each one has a specific use.
a - Add line. This block will add a line of blocks to the field it's directed at. (Offensive use.)
c - Clear line. This block is the opposite of the a block. Its purpose is to clear a line from the field it's directed at. (Defensive use.)
n - Nuke field. This block will clear a field of all its blocks. (Primarily for defensive use.)
r - Random block clear. This block subtracts random blocks from the field it's used on. (Offensive use.)
s - Switch fields. This little gem is the brat of the whole game. Use this block to switch your field with an opponent's. (Offensive/defensive use.)
b - Sterilize field. This block is used to change the "special" blocks to normal blocks. (Offensive use.)
g - Gravity. This block will cause all the floating blocks to fall to the ground, one atop the other. (Defensive use.)
q - Quake. This block will, well, basically cause the blocks on a field to zigzag. (Offensive use.)
o - Bomb. This block can only be used properly if you or an opponent have another "o" sitting in your field. It will effectively "blow up" the blocks around it, sending them into the sky to float until either cleared, or gravitized.
11/12/03 - ver. 1.0 | This is my custom, personal TetriNET theme. (I will have it available for download, soon.) The image seen here is the actual size of your playing field. (It may be desireable to reduce your screen dimensions for a larger playing field. I, myself, used to play under 800 x 600.) Check back for future versions of my theme.
Download ver. 1.0