Mauzeraut
Scenario:
Planet Earth, modern era. Xenomorphs begin with a single queen somewhere in the amazon, Flood begins with a single organism somewhere in Mongolia.
Assume both races act like they would in their story element... automatically hostile to everything but themselves, Aliens gain power as they process more genetic material, flood gain power as they process sentient life.
Bearing in mind, Xenomorphs are natural bad-*ssed killing machines even without any strategic element. Flood, on the other hand, need to progress for a bit before they become really terrifying, able to make tactical and eventually strategic decisions, wield and use modern weapons, reach a certain amount of sentient biomass to create a "gravemind" (think omnipresent general), etc.
For fun you can include the human element (armed resistance, nuclear response, exodus and containment, etc).
Planet Earth, modern era. Xenomorphs begin with a single queen somewhere in the amazon, Flood begins with a single organism somewhere in Mongolia.
Assume both races act like they would in their story element... automatically hostile to everything but themselves, Aliens gain power as they process more genetic material, flood gain power as they process sentient life.
Bearing in mind, Xenomorphs are natural bad-*ssed killing machines even without any strategic element. Flood, on the other hand, need to progress for a bit before they become really terrifying, able to make tactical and eventually strategic decisions, wield and use modern weapons, reach a certain amount of sentient biomass to create a "gravemind" (think omnipresent general), etc.
For fun you can include the human element (armed resistance, nuclear response, exodus and containment, etc).