  We analyze Solo Chess puzzles, where the input is an $n \times n$ board
containing some standard Chess pieces of the same color, and the goal is to
make a sequence of capture moves to reduce down to a single piece. Prior work
analyzes this puzzle for a single piece type when each piece is limited to make
at most two capture moves (as in the Solo Chess puzzles on chess.com). By
contrast, we study when each piece can make an unlimited number of capture
moves. We show that any single piece type can be solved in polynomial time in a
general model of piece types, while any two standard Chess piece types are
NP-complete. We also analyze the restriction (as on chess.com) that one piece
type is unique and must be the last surviving piece, showing that in this case
some pairs of piece types become tractable while others remain hard.
