The whole idea isn't that easy at all depending on your actionscript competance. One option might be to find an open source flash version and skin it, that's where all those bloody space invaders games come from, but sadly I don't know one similar to the one your after.
You want to do it yourself check out these sites...
http://www.kirupa.com/
http://www.actionscript.org
You need to be looking at the tutorails which describe captuing user input, via the mouse or keys. Movieclip duplication and creation. Colision detection and moving movieclips using scripting.
If you want proppa first person you'll need 3D - not easy at all...
http://www.kirupa.com/developer/acti...pt/3dindex.htm
Might be a good idea to grab yourself something like this too...
Flash Game Book
can't vouch for that one in particular I learnt using an older one called flash games studio which is a bit out of date now
