There are realistically only a few 'verbs' players have in combat: Shoot, Throw, Build, Move. Shooting slows down the player to considerable degree and is therefore the highest risk action. Oddly enough, the higher tier upgrades to shooting weapons usually involve vastly faster firing rates, which have the effect of encouraging the player to sit in the punishing 'slow' state for longer. Throwing has no disadvantage and can replace or be done in conjunction with shooting.
TL;DR
Basic attacks should do more than simply damage biters/spitters and should negatively impact their performance in some way.What ?
There should be a light flinch/stun/slow/animation/fear response when biters get hit with basic weapons, followed by a short (not instant) acceleration back to normal speed. Biters taking continual high damage should likely have movement stopped and their attacks interrupted.This is a classic gameplay effect often seen in old shooters with hitscan weapons.
The percentage of damage done to the enemy could be used as threshold or modifier to length of time.
Why ?
The immediate benefit is that this gives players better visual feedback and game feel in combat. Individual shots have more weight, the player has greater control over targets.I would suggest this effect would mainly apply to bullets and explosives:
Pistol would keep a single medium biter safely off of a player.
SMG could likely be used to sweep repeatedly across multiple targets.
Shotgun and grenades could hinder the front rank of a crowd.
Rapid fire rockets or tank rounds could stunlock a Behemoth.
I am purposefully leaving lasers off of this, to keep the existing implementation of personal laser defenses from becoming ridiculous, and to perhaps differentiate the tower weapons a bit.
Balance wise, yes, this will make the current game considerably easier, but remember that biters rarely attack solo. Weapon rates of fire (especially with upgrades) are currently a bit overbearing and will likely need to be toned back.