Why is this line of PHP causing this error message? (see details)?

This line:

unset( $this->'game' );

is causing this PHP error message:

Parse error: syntax error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting T_STRING or T_VARIABLE or '{' or '$' in /home/public_html/games/inc/scrap.php on line 646

Can someone please tell me how to correct this?

Thanks

Took me awhile to learn sadly but every time you see Parse error its usually a mistake on your part with ; or " in the wrong spot.