Greetings! I have an idea for a game so I'm doing some research to work out the basic mechanics. So, I was wondering if there is a fundamental difference (from a mechanics stand point) between pierce and penetration? 

When a thing is pierced, the thing that pierced it has come all the way through. For example, an arrow. If the point has passed all the way through the target and the point is in the air again. Did you try Googling the definitions?

Ok that makes sense! Yes, however since some games use pierce in the context of ignoring def, I was wondering if there was a fundamental reason for using that way. The way you summarized it gave me an idea to use both. Thank you! 

Since Pierce and Penetration can be whatever you want in your game, why not decide what they do instead of relying on how other people made them work in their games? Maybe some dude says Pierce ignores defense, but what if you want Pierce to ignore buffs instead? You're the creator, and those terms aren't set in stone.

When a term is well established, players have certain expectations from it. It's a good idea to follow that expectation. For example, if every game ever uses "critical strike" to mean "deal increased damage", and you redefine it to mean "deals damage over time", players will be confused. So be careful with "it can be whatever you want".

In some games (particularly TBS ones), pierce is used to indicate that an attack deals damage to all enemies within range (or sometimes just more than one, it depends) while penetrating is generally used to indicate overcoming defense.

Necro. Locking thread.