Infected is not like the typical "one man army" zombie survivor game. Where as the single player can be played and enjoyed alone, it is best suited to be played with friends. I felt that the ONLY zombie games were multiplayer (L4D and a few other zombie mods) and couldn't be enjoyed for BOTH their single and multiplayer content. I hate calling Infected a zombie game as the enemies aren't undead but it will probably be called that anyways.
Just a quick mockup of the HUD, will most likely be changed.
1 - Party Member Display
1a - Steam Icon/ NPC icon
1b - Party Member Name
1c - Current weapon party member has equipped
1d - Party Member Health and Infection Rate
2 - Inventory *Is semi-transparent while in use and dissappears after 5 secs of non use*
3 - Health
4 - Infection Rate
5 - Ammo left in clip/total ammo left. *Gray part is type of grenade you have and the amount*
6 - 2nd weapon