If it is a combination of predefined values consisting of both numeric and string values nicely stashed up in a structure, I'd suggest using a combination of a serializer like Storable and a simple binary-text converter like builtin pack.

use Storable qw( nfreeze thaw );
my $game_data = {
    score    => 1425,
    hits     => 3,
    name     => "Supernova",
    accuracy => 0.34,
    :
    :
    };

my $enc = unpack "H*" => nfreeze ({ game_data => $game_data });
# $enc now contains something like
# 05080300000001040300000004088300000004686974730a0953757065726e6f7661
+000000046e616d6509000005910000000573636f72650a04302e33340000000861636
+375726163790000000967616d655f64617461
[download]

On the receiving side, other way round ...

use Storable qw( nfreeze thaw );
my $game_data = thaw (pack "H*" => $enc)->{game_data};
[download]

It is up to you to decide how <c>$enc gets transported between the games.