Copyright (c) 1991 Rainer Knizia

This game is played on the following board:

STONE LIMIT: Each player starts with 13 stones.
MOVE - There is no pass, the player must do one of the following things:
Drop a stone on any empty cell at the bottom row.
Move up one row, if there is one stone below the destination cell.
If one piece has no stones below it, it must move down one row.
GOAL - Wins the player that moves into the top cell (marked with the red dot) or is able to stalemate the opponent.

A remark: If there are 2 stones at top of the pyramid, the player can move one to the goal cell and win. But only, if he is not forced to fall down with one of these pieces! However, is is possible to make the winning move, if there is a further falling piece in another level of the pyramid. Because in this case, the player are not forced to fall down with the piece at the top level of the pyramid!

An example

Despite the apparent disadvantage, Green can win in 6 moves, by dropping at cell e5 [1]. Then, f6-e6, d5-d6, e8-d8, d5, h8-g8, f7-f8, g7-f7, e5-d5, g8-g7 (the stone falls), f8-e8 and wins by stalemating Violet.

There is a ZRF to play Pyramid with Zillions.