Prerequisite: Alien Aliens and prehistoric monsters come in all shapes and sizes. When facing gigantic creatures such as a Tyrannosaurus rex or a Wooly Mammoth, or tiny foes such as Compsognathus, the Gamemaster may wish to include some additional rules to take their size into account.

• Tiny (Major Bad): Only a few centimetres long. Tiny creatures are things like most insects and vermin, as well as mice, rats, most lizards and snakes—anything that’s small enough to hide in your boot or pocket. Tiny creatures have a maximum Strength of 1, and a single point of damage is enough to squish a Tiny creature. Marksman-based attacks on Tiny creatures suffer a -4 penalty (or more—you try shooting a mosquito out of the air with a sniper rifle!) and -8 to notice them.
• Small (Minor Bad): These creatures are noticeably smaller than an adult human. It covers most cats and dogs as well as a great many dinosaurs. Human children are also Small. Small creatures have a maximum Strength of 4; most will have a Strength of only 1-2.
• Average: We’re being a bit self-centred by calling the human species ‘average’, but anyway, this covers adult humans as well as any creature that’s roughly our size, like apes, big wolves, crocodiles, raptors… Average creatures have a maximum Strength of 7. This isn’t a trait at all, really, but it’s here out of a sense of completeness.
• Big (Minor Good): This is a creature roughly the size of a horse or gorilla, like a bear or a Dracorex or a Gorgonopsid. If it’s bigger than a human, but can still hide from you, it’s Big. Big creatures have Strength scores of up to 12.
• Huge (Major Good): Huge creatures are really big. Elephants are Huge, for example, as are most of the big dinosaurs used by the Silurians like the T-Rex or the Triceratops. Huge creatures have Strength scores up to 16.
• Colossal (Special Good): There aren’t any Colossal creatures in the modern day outside the oceans, but during the Age of the Dinosaurs there were titans like the Apatosaurus. These creatures have no upper limit on their Strength scores, and attacks on them are like shooting a barn door – you get a +6 bonus when shooting at a Colossal creature (but it probably won’t notice).

Size has one key effect on combat: if there’s more than one size category between attacker and defender, the bigger creature has to use Coordination when making melee attacks. That means that even if an Apatosaurus has a Strength of 16, it can’t automatically squish a tiny human. Instead, it has to roll Coordination + Fighting to hit. It can, however, bring its full Strength to bear on a bigger target; like, say, a T-Rex. Or a tank. This also applies to humans; you can’t just use your Strength to attack a Tiny creature, you have to use Coordination.