+1 Goggles

Possibly the best thing about making a FPS in Unity, is that someone has more than likely done what you're thinking of doing, or at the very least something that can help you.

That said, with a little bit of poking and bug fixing my game now has;
A (mostly) completed gun script. (its a laser beam :D)
A working ammo counter.
Ammo Pickups.
Big red cylinders you can shoot at.
All this avaliable here

While I'm here I may as well talk about some of the things that have influenced this Sci-Fi shooting gallery.
First of all my aim for this years final major project was to have a playable game (which it currently is) the other games I had designed for this were;
Lumberjack Attack: A 16-bit Robot Unicorn clone featuring a butch lesbian lumberjack as the protagonist
Unnamed RPG: Final Fantasy type with elements from Legend of Dragoon.

One of these would have been easy to make but lacking in level design and the other would have been a bit of a pain and would have had a lot more level design. I decided to settle on my 3rd idea, You are not unique. This idea was inspired by games like Mass Effect and Halo, with some HL2 thrown in for good measure. More recently I have added in some elements from the Warhammer 40,000 franchise, the weapons for example (Lasguns of the Imperium) and the infantry wearing advanced armour (Tau infantry) of which my protagonist will be.

The level I decided to make was the opening level, like Halo it is based aboard a spaceship and has the main character fend off alien boarders, originally it was split into 3 parts, a landing bay/cargo part, an arboretum and finally the ships main reactor. Now I will only be making the first part and iterating it as many times as I can, hopefully having something awesome at the summer show.