The basic concept is fairly simple -- there are two players, one of whom plays a nearly standard game of tetris, the other chooses which pieces his opponent will get.
Since play is asymmetric, a full game consists of two rounds, with each player acting as the piece-dropper once, and as the piece-picker once.
Whoever has the higher score when playing as the piece- dropper wins the game.
To avoid making the game either excessively hard or easy, the piece chooser is initially quite constrained in how he can dispense pieces, and these constraints are relaxed slightly each time the piece dropper finishes a level (every ten lines).
Of course, the game still speeds up with level completion, just like regular tetris.
The piece chooser, playing on a separate computer from the dropper, sees both the tetris 'well', and a piece selection editor. On each row of the editor are seven pieces, one of each tetromino. Pieces can be dragged left or right on the line to make them occur earlier or later.
The piece dropper is dispensed tetrominoes from the top row of the editor, leftmost first.
Each time the piece dropper is given a piece, it is darkened in the editor, and cannot be moved. When an entire row is darkened, it is removed from the editor, and a new row is added to the bottom of the editor area, moving everything up.
The above is not enormously different from how piece choosing is restrained in the standard game of tetris. Obviously normal tetris doesn't have someone maliciously reordering pieces, but even so, it's possible for a skilled piece dropper to play indefinitely, if he's got time to plan ahead. Notably, the longest number of tetrominoes that can occur between two 'I' pieces is 12, and the longest run of consecutive 's' and 'z' pieces is 4.
Starting with level two, the rightmost column of the piece chooser's editor gets greyed out. Pieces can still be dragged there, but only the first six on each line will be used. If the piece chooser wants, he can put all the 'i's on the right, and never give them to the piece dropper.
On level two, an additional column in the piece choosers editor is grayed out.
Etc..
On level six, the rightmost 5 columns of the piece choosers editor are greyed out, which means that, if he wants, he can give continuous alternating 's' and 'z' pieces to his opponent, which has been mathematically proven to force the game to end after at most 150 tiles, though in practice happens much sooner.
On levels eight and above, the only thing which changes is the speed of the game. Getting that far is unlikely, if the piece chooser isn't stupid.
This idea was inspired by Hatetris (not to be confused with Hatris), where the pieces are chosen by the computer, in a non-random manner, to make it hard for the player to get lines.-- goldbb, Oct 04 2015 Hatetris http://qntm.org/fil...etris/hatetris.htmlEvil Tetris [goldbb, Oct 04 2015] Ah - so, not a game in which unborn children must be fitted together, then.-- MaxwellBuchanan, Oct 04 2015 Maybe it needs a hyphen in the name?-- goldbb, Oct 04 2015 What if the piece dropper were your friend? And wanted to help? What then? WHAT THEN??!
good to read a goldbb idea. Never drivel.-- bungston, Oct 07 2015 +-- pashute, Oct 09 2015 Yes, it needs a hyphen in the name.-- pertinax, Oct 10 2015 I had the same thought as [MB], so it can happen, but possibly unlike him, I do want there to be a game in which unborn children are fitted together.-- nineteenthly, Oct 12 2015 random, halfbakery