[jtrkhsxz] Big bang chess

Consider a chess variant where in the initial position, the board is entirely occupied with pieces, no empty squares.  The game begins with a bloodbath of captures until there is enough space for pieces to move around strategically.

Checkmate might be too easy at the beginning.  One alternative is playing until one player gets annihilated, or has less then some threshold number of pieces.  Or perhaps the king gets dropped in in the middle of the game, at which point, the player's pieces gain abilities, but loss by checkmate becomes possible.

Let all the pieces be isotropic, no pawns or promotion.