It's not a rip off of any computer game. I actually got the idea from a Christmas present.
If you want to add players type "default formation" in as Player 2's name then next time you run it you should have 11 players. To customise your formation and team name look at the website at
http://www.geocities.com/madmattgames/pf/index.htm
for more information.
I have actually made a rip off of an amiga game though. Witch Bomber was a rip off of my brothers game for the amiga, which itself was supposed to be a "Halloween version" of New York Blitz for the Spectrum.