I definitely think it could be. It's a design decision, of course, and however you prefer to code is the best way at first.

Here's a what might be a better analogy: file types. You could definitely have a Perl module family for them where you had FileType::Text, FileTypeXML, FileType::Executable::Perl, etc but you'd end up with way too many, obviously, and then you'd also end up stuck trying to accommodate data types that are half-in-half-out of filedom, FileType::ApplicationVnds, FileType::OctectStream...

When you consider that, MIME::Types is obviously superior and a natural partner for whatever specific datastore (file, scalar, stream, db record) or parser.

And since you happened to have hit something I'm interested in, here's a prototype to see one way it could be done. I left out Moose roles and traits as they get kinda hairy. This has some idiomatic Perl in it but also a nice terse tour of some really cool nooks.

# ---------------- path/to/lib/MyRPG.pm
package MyRPG;
our $VERSION = "0.01";
use MyRPG::Die;
use MyRPG::NPC;


# ---------------- path/to/lib/MyRPG/Die.pm

package MyRPG::Die;
use Moose;
use Moose::Util::TypeConstraints;

has "sides" =>
    is => "ro",
    isa => enum([qw( 4 6 8 12 20 100 )]),
    required => 1,
    ;

around BUILDARGS => sub {
    my $orig = shift;
    my $class = shift;

    if ( @_ == 1 && ! ref $_[0] ) {
        return $class->$orig(sides => $_[0]);
    }
    else {
        return $class->$orig(@_);
    }
};

sub roll {
    int(rand(+shift->sides))+1;
}

__PACKAGE__->meta->make_immutable;

1;

# ---------------- path/to/lib/MyRPG/NPC.pm

package MyRPG::NPC;
use Moose;

has [qw( name type )] =>
    is => "ro",
    isa => "Str",
    required => 1,
    ;

has "hitdice" =>
    is => "rw",
    isa => "ArrayRef[MyRPG::Die]",
    required => 1,
    auto_deref => 1,
    ;

has "hitpoints" =>
    is => "ro",
    isa => "Int",
    default => sub {
        my $hitpoints;
        $hitpoints += $_->roll for +shift->hitdice;
        return $hitpoints;
    },
    lazy => 1,
    ;

has "current_hitpoints" =>
    is => "rw",
    isa => "Int",
    default => sub {
        +shift->hitpoints;
    },
    lazy => 1,
    ;

sub damage { # This would be trait/role/type/armor/alignment influence
+d!
    my $self = shift;
    my $attack = shift; # Should be an object, we'll just call it raw 
+points.
    $self->current_hitpoints( $self->current_hitpoints - $attack );
}

sub dump {
    my $self = shift;
    my $line = "-"x50;
    sprintf("%s\n%20s -> %s (%dhp)\n current hitpoints: %d (%s)\n%s\n"
+,
            $line,
            $self->name, $self->type, $self->hitpoints,
            $self->current_hitpoints, $self->status,
            $line);
}

sub status {
    my $self = shift;
    $self->current_hitpoints <= 0 ?
        "dead" : ( $self->current_hitpoints < $self->hitpoints * .3 ) 
+?
        "not so hot..." : ( $self->current_hitpoints < $self->hitpoint
+s * .8 ) ?
        "s'okay" :  $self->current_hitpoints != $self->hitpoints ?
        "tip top" : "never better";
}

__PACKAGE__->meta->make_immutable;

1;

# ------------------- some test code in a regular executable

use warnings;
use strict;
use MyRPG;

my $six_sided = MyRPG::Die->new(6);
print "Warming up the bones... test roll $_: ", $six_sided->roll, $/ f
+or 1 .. 3;

my $npc = MyRPG::NPC->new( name => "CmdrTaco",
                           type => "SwampYankee",
                           hitdice => [ ( $six_sided ) x 3 ] );

print $npc->dump;

my $dodecahedron = MyRPG::Die->new(12);

print "Take that, ", $npc->name, $/;

$npc->damage( $dodecahedron->roll );

print $npc->dump;
[download]

Sample output-

Warming up the bones... test roll 1: 5
Warming up the bones... test roll 2: 2
Warming up the bones... test roll 3: 4
--------------------------------------------------
            CmdrTaco -> SwampYankee (16hp)
 current hitpoints: 16 (never better)
--------------------------------------------------
Take that, CmdrTaco
--------------------------------------------------
            CmdrTaco -> SwampYankee (16hp)
 current hitpoints: 6 (s'okay)
--------------------------------------------------
[download]

I'm kinda glad I am out of time today. This probably would have eaten up a few hours. :) As it is, that took me almost exactly 30 minutes to put together (I have an RPG background though, obviously). Viva la Perl!