Kolakoski

Score: 72.12 (pass)

#!perl
$$=pop;$.=$ARGV[$|--],$_.=$.x substr$_.$.,$*++,1while!/.{$$}/;print$&,$/

Score: 72.16 (pass)

#!perl
$l=pop;$.=$ARGV[$|--],$_.=$.x=substr$_.$.,$o++,1while!/.{$l}/;print$&,$/

Score: 75.15 (pass)

#!perl
$l=pop;$.=$ARGV[$|--],$_.=$.x substr$_.$.,$o++,1while!(/.{$l}/&&print$&,$/)

Score: 77.19 (pass)

#!perl
$l=pop;$.=$ARGV[$|--],$_.=$.x substr$_.$.,$o++,1 while$o<$l;print/(.{$l})/,$/

Score: 106.25 (pass)

#!perl -l
$l=pop;($x,$y)=@ARGV;while(length$_<$l){$q=($|--?$y:$x);$_.=$q x substr$_.$q,$o++,1}print substr$_,0,$l