use lib "path/to/Chess path/to/Chess/Piece";

In this case, when you try to use Chess::Piece, Perl would look for "path/to/Chess path/to/Chess/Piece/Chess/Piece.pm" — so that likely won't work.

Perl essentially does the following to create the full path:

use lib "searchpath";
use                 Chess::Piece;
                   /     /      .pm
=>      "searchpath/Chess/Piece.pm"
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