Okay, so. A video game is, by its very nature, going to be much more abstracted than actual history. Especially when you consider the 'rock/paper/scissors' nature of a lot of game design.

Spears were an ubiquitous weapon up into the widespread use of firearms, and even in the mid 1800's you had units getting armed with spears and pikes when nothing else was available. It makes sense, too, as a spear is relatively easy to make, compared to a sword. Since polearms of various types/varieties were so widespread throughout the world, it's hard to really boil things down to 'sword beats spear' or vice versa.

What was more important was stuff on the unit scale; training, cohesion, morale, etc. One guy with just a spear is just ... well, a guy. 1000 guys with spears can fight as a unit, and work together. However, if that block of spearmen can't fight in formation like they're used to doing because of the terrain, or if they break and run at the first showing of the enemy, you're going to have problems.

A book you might find interesting on this subject is Myke Cole's 'Legion vs. Phalanx.' It breaks down several different battles between Roman legions and Post-Alexandrian phalanxes. Neither style of army proved inherently superior than the other-- more often than not, the battles Cole describes were won by elephants or heavy cavalry. This said, the phalanxes of the time used long, pike-like spears, while the Romans relied more on javelins and swords. When a phalanx could hold together, it could present a deadly hedge of spearpoints-- in one direction. However, if a phalanx could be flanked, or if rough terrain prevented them from keeping a tight formation, the legionnaires could get in past the long spears and start stabbing.

I imagine this is kind of what the Total War games are going for? But again, spears are such a universal weapon across cultures that it's impossible to make broad 'paper beats rock' generalizations. In actual history, battles were more often decided by who had the most advantage (training, numbers, terrain, etc) instead of who was carrying what kind of weapon.