no no
no no
Marines vs UPP with xenos on the side
Starting from scratch is a big question since there's no way of knowing if your interpretation would end up being popular or good enough.
If I were to start from scratch, and assuming I had a god like level of coding/mapping/spriting competence (or a team of slaves to do that), I would try to utterly revamp the core CM experience.
Its a concept I've only mulled over on rare occasion, but the general idea would be to focus more of the game on the ground and place a far lesser emphasis on there being a ship/Almayer. The game would focus on a company of Marines on a planet and they are trying to clear out the colony of Xenomorphs, the ranks would go as high as a Field Commander, but most people would be apart of smaller squads ranging from five to ten people.
I'd try to emphasize slower, more thought out, gameplay. Movement would be slower, the map would be very CQC focused and very dark, everything would be highly lethal, gunfire would be more lethal than it is now (I'd argue most xenos would die in 2 burst fires) but Marines would also die very fast in melee against a Xeno. I'd even argue for directional vision and directional lighting (like flashlights on CEV Eris) and a unique vent system that functions like CEV Eris, Corp Merc or Lifeweb where xenos can jump into vents above the play field and drop down on Marines.
Xenos would be supplemented with a larger array of NPC Xenos, easier and weaker but a good force multiplier, and to give Marines something to shoot and distract them. Xenos would be able to respawn at a steady rate after dying (perhaps a faster respawn if more Marines are captured). Captured Marines are just killed off once they are 'processed' and the dead Marine is encouraged to become a Xeno or wait for a Marine reinforcement wave.
Who knows, it's more a dream game.
This is war, survival is your responsibility
Captain Alan Bentway
Synthetic: Nicholas
Hunter Kwei Ikthya-de