Kolakoski

Score: 65.22 (pass)

#!perl -l
$_.=($k=$ARGV[$i&1])x(/./g,$k)[$i++]until/.{$ARGV[2]}/;print$&

Score: 66.23 (pass)

#!perl -l
$l=pop;$_.=($k=$ARGV[$i&1])x(/./g,$k)[$i++]until/.{$l}/;print$&

Score: 69.22 (pass)

#!perl -l
$l=pop;$_.=($k=$ARGV[$i&1])x((/./g)[$i++]||$k)until/.{$l}/;print$&

Score: 74.22 (pass)

#!perl -l
$l=pop;$_.=($k=$ARGV[$i%2])x(/.{$i}(.)/?$1:$k),$i++until/.{$l}/;print$&

Score: 84.21 (pass)

#!perl -l
($_,$,,$l)=@ARGV;$_ x=$_;$_.=$ARGV[++$i%2]x(/.{$i}(.)/?$1:$,)until/.{$l}/;print$&