Object: Checkmate the opponent's King by attacking it so it cannot escape.

In this Chess variant, the board is filled up equally by duplicated pieces from each side. In the included 150 subvariants, four of the extra pawns are replaced instead by another copy of each of the four stronger pieces; Knight, Bishop, Rook, and Queen. A remaining 4th row empty square per side counters the non-duplication of the King piece.
After an initial capturing stage, an unorthodox piece alignment(s) will likely exist, i.e. multiple pawns in a column or an extra (or more) stronger chess piece.

A setup note: each side's 3rd and 4th rows are filled by the duplicated chess pieces in a random order. Click the Pass button or an empty square area to start.

Three well-known chess variants have been adapted here as subvariants:
Extinction Chess by R. Wayne Schmittberger,
Non-Prise Chess by Bruce Zimov ('Specific' rules have been modified for this game),
Take-All Chess.