A simple injury system would be a great addition to Deadside.
Serious injuries could leave blood trails. Falling from a great height or getting shot in the leg could cause players to limp for a short time, while arm injuries could reduce aiming stability or slow down reloading.
This would make healing items more useful and fights more tactical, because injured players could not push immediately. Groups with a numerical advantage would not have an instant advantage.
The system should stay simple and not become overly complicated.