Here's a quick guide, for those already playing the mod or wanting to play.

Vengeance -> Vanilla + epic hordes
Scavenger -> Vengeance + Restricted weapons&Aliens drop weapons

===============Colors===============
Black -> Speed
Red - > Boss
Pink -> Weak
Orange -> Explosive
Yellow -> Movement
Green -> Hive
Blue -> Carriers
Purple -> Poopers&TheRest

===============Types===============
Bigger -> More health
Smaller -> More speed

Elite Wave -> Scary text, that indicates a very strong elite wave is comming
Example -> Feast, Rise, Dark fire, for the night, apocalypse, drums in the deep
Result -> Paras, Zombies, Red stuf, White walkers, Barrelparty, Goblins

Carriers -> Drop aliens upon death
Hives -> Keeps pooping aliens
Poopers -> Keeps pooping eggs/barrels/fires

Single Black Wanderer ->
upon death, surrounds you with drones/rangers/harvys or boomers

New models:

Antlion = a new insect type, not that big charger (antlionguard)

Antlion -> Around 10 damage, 1 health
Zombies -> Around 10 damage, 200 health
Headcrabs -> Around 10 damage, 1 health
Black Zombies -> Nearly 1 hits , 500 health
Black Headcrabs -> Nearly 1 hits, 1 health

===============Changes===============
- Less alien health & damage than vanilla
- More alien speed than vanilla

- Gl nerfed damage for non explosive characters

- Ammo&medpack drops

==========Changes for scavenger==========
- Halfed horde sizes

- Restricted starting weapons&equipment

- Aliens drop weapons&equipment

- No class restrictions

==============How to play==============
Servers hosting:
- Rara's server
- DMW's server

Or download yourself:
Workshop -> Scavenger (this modpack has both modes)