To expand on this, Tecmo Bowl had 12 teams, I believe, and was released in 1989. Teams would play either 7 on 7...or 9 on 9 and you only had 4 plays to choose from.
Tecmo Super Bowl had all 28 teams and was released in 1991, 11 on 11 formations and 8 offensive plays....and is tied with NHL94 for the greatest video game of all time.
Dominant Teams:
San Fran - The Montana to Rice connection was unstoppable. It wasn't uncommon for Rice to make catches in triple coverage.
Houston - Strong passing attack led by Warren Moon & speedy recs.
Buffalo - Great all around team.
NY Giants - another great all around team.
Philly - QB Eagles can frustrate any defense.
LA Raiders - Bo Knows Tecmo.