Here is a simple networked two-player variant of tetris - with a couple of twists. Instead of two separate boards, the players play on the same board, with their pieces falling in opposite directions; and they have some control over the pieces their opponent gets (by having the ability to select a piece that won't be spawned in the next turn).
Left...................................Right -------------------------------------------- |..........................................| |...x............................oo........| |...xx.---->...............<----.oo........| |...x......................................| |..........................................| |..........................................| |..........................................| --------------------------------------------Your pieces do not fall until the end of the board, it is stopped some steps before the another player's wall.
Left...................................Right ....|.<--right player's piece ....|....will fall until this line -------------------------------------------- |..........................................| |.....x..........................oo........| |.....xx.--->..............<----..o........| |.....x...........................o........| |..........................................| |...OO.....................................| |...OO.....................................| -------------------------------------------- ..........left player's piece----->.| ..........will fall until this line.|If two pieces "meet" somewhere on the board, the current player's piece is stopped. The next player has the chance to move away, however she doesn't do so her piece will be also stopped. If a piece stopped, a new piece generated and started from the player's starting wall. The stopped piece become a stationary wall. Example of stopped pieces on the board
Left...................................Right -------------------------------------------- |..........................................| |...x............................oo........| |...xx.---->...............<----.oo........| |...x..............O.......................| |...............XXOO.......................| |................XXO.......................| |..........................................| --------------------------------------------
Left...................................Right -------------------------------------------- |................XX........................| |................XOO.............oo........| |..............x.XOO.............oo........| |.........--->xxx..O.......................| |.............X.XXOO.......................| |.............X..XXO.......................| |.............XXOOOO.......................| -------------------------------------------- Next step: Left...................................Right -------------------------------------------- |.................X........................| |.................OO.............oo........| |................XOO.............oo........| |...............XX.O.......................| |..............X.XOO.......................| |..............X..XO.......................| |..............XXOOO.......................| --------------------------------------------In the example above the left player got 6*1 + 1*5 = 13 points. After a column is destroyed, the stationary wall "over" the destroyed column fall towards the other player's wall. The stationary wall "under" the destroyed column DOES NOT move anywhere.
Left...................................Right -------------------------------------------- |...................................XX.O...| |...x................................XXO...| |...xx.................................OO.o| |...x..............O................XXXOOoo| <--- piece cannot leave the wall |...............XXOO................X......| next step it will stop |................XXO.................XX.O..| |....................................XXOOO.| --------------------------------------------