I made a new, better looking HUD.
Normal HUD:
Weapons purchase HUD:
Ammo purchase HUD:
Upgrades HUD:
Fades when aiming down sights:
In ammo I imagined that you could purchase throwing knives as well.
Stats and rank show stats and rank (playtime, kills, headshots, leaderboards e.t.c.)
Rules show rules, build number, creators and stuff like that.
Items acts like a toned down 'Q' menu where you can spawn some crap.
Always have crowbar.
Hide ammo crates around the map.
Look closely on each menu to find details that may be vital.
That's basically my idea. It's a bit much, buuuuuuuuut... the gamemode has freaking potential. Use it.