Just replayed Extinction a few days ago.
Found it somewhat mediocre and the class designs for the species confused me.
Ran around a bit and tried thinking of how I'd rework the existing Extinction mechanic...
For the Aliens it seems pretty daft to have the caste classes determined by host. Especially considering you can't control what hosts are available in an area. That's just stupid biologically. What if I only have oswocs near me? My hive is doomed as it's filled with combat inefficient Drones.
That needs to be scrapped.
The Aliens should be divided into several categories within Transbreed type. These categories belong to physical castes. Within these castes the Aliens can vary a little depending on host. However, they still maintain similarities in combat efficiency and role. The Alien caste should be determined by spending points on eggs (somewhat like with Praetorians, except the facehugger is the same).
Workers - The same as the Drone class in the game. They are small, albino Aliens with no armor and physical weakness. Upgrades result in acid spit and the cysts. Creating Workers takes no points at all.
Soldiers - Based on the Warrior class in AvP:E. Pretty good for everything - they explode when killed in an acid shower. Upgrades are the same as in the game. They can revive when not burned, have better weapons, etc.
Scout - Based on Runner class. Very low health and strength, but extreme speed and senses, super fast health regen outside of hive. Have a leaping attack. Upgrades are the same: poison. All Aliens are quadropedal, regardless of host.
Different hosts cause slight variations in all of the Aliens above mentioned.
Humans - The Aliens like we see in the films. They are good in all stats, but excel in none.
Oswocs - Bulkier and slightly slower Aliens that have more health. Born Aliens are mostly quadropedal, but can walk bipedally at will (except Runner).
Kurns + Kriltics - Smaller Aliens with less health and slightly increased speed. Prefer quadropedal movement but can become bipedal at will.
Predators - As the hardest species to get hosts from, Aliens born from them have an extra bonus.
-Superior to all other hosts in all categories. Better health, speed, and attack power. Aliens are slightly bigger and have mandibles (dreadlocks?).
-A special upgrade allows Predator born Aliens to gain XP and become more powerful.
The Predators are also kind-of iffy, as you have these retard Predators that only use a single weapon despite the portability of all their equipment, and these military Predators that are so powerful that you don't need the others, you can just spam the military types.
IMO, the Predators should be less class based than the other species.
The Predators could have different classes with different abilities with weapons, but generally speaking Predators should all have long range weapons + melee weapons.
The Predators should be based on XP - you use points to bring a Predator into the hunt, and this Pred starts at level 1. As he fights he gains XP with his weapons and earns points towards upgrades for HIS weapons. Increasing a level allows a Predator to do more damage with his weapons (implying greater skill/accuracy with their usage).
I'm unsure of what I think of the Shrine. It feels somewhat different to the other species who all revolve around one member of their species - but I honestly think some sort of Elder or hunt Overseer or whatever you want to call it could be preferable.
This overseer would essentially be a Predator with full XP, the most advanced weapons, and a Predator with access to the ship, whom can give permission to other Predators to join the hunt.
In terms of classes I guess you could have Predators that are better with some weapons and worse with others, and whose arsenal varies.
You could have a "crowd control" class that has a Smart Disc, Dual Shoulder Cannos (fire weaker shots are more targets?) and the Combistick.
A melee class - that is at his best with wristblades, combistick, and starts with whatever other melee weapons you could have, and only has a standard shoulder cannon for long range.
A sniper class that employs the Speargun and has a longer cloaking field (the cloaking field could also be something that can be upgraded).
I'd honestly give the Predators the biggest overhaul in terms of gameplay. They also shouldn't get points for screwing around with hopeless animals like oswocs. As a result the Predators play like conquerors fighting for resources.
I don't really have all that many thoughts on the humans... I don't find them too bad, but in the higher difficulties they are so underpowered they are impossible to play with offensively (but then again, that's really only against the Predators and their stupid f**king Hydras) so take that as you will.
Come to think of it, the humans and the method with which they gain money is absurd. Killing earns you almost zippo, and the ATMOs don't come back. I'd rework that. Just as the Aliens can harvest regenerating resources, so should the humans.