Kolakoski

Score: 58.16 (pass)

#!perl
$;=pop;s/.?/$ARGV[1&pos]x($&||1)/eguntil/.{$;}/;print"$&
"

Score: 58.18 (pass)

#!perl -l
$;=pop;s/.?/$ARGV[1&pos]x($&||1)/eguntil/.{$;}/;print$&

Score: 59.22 (pass)

#!perl -l
$l=pop;s/.?/$ARGV[1&pos]x$&||1/eguntil/(.{$l})./;print$1

Score: 81.22 (pass)

#!perl -l
($",$e,$l)=@ARGV;$_=$"x$".$e;$c=1,s/./(++$c%2?$e:$")x$&/eguntil/.{$l}/;print$&