Orthogonal Unit Differentiation and Hit-Scan Weapons

If you haven't heard of the Game Maker's Toolkit, you should check it out as it offers some excellent insight and explanation of some big topics related to game design, and it does so with some super-slick editing that oozes careful creation. In particular, his video on Doom has some fascinating info on what truly made it so special: something called "Orthogonal Unit Differentiation", which is a term used to designate the practice of designing enemy types that are distinct in their abilities, appearance, and audio/visual presence, e.g. the difference between Doom's Imp, Cacodemon, and Lost Soul versus Battlefield's enemy dude, enemy dude, and other enemy dude.

It's obvious, but I had never really considered that the design of the enemies as distinct entities with wildly different strengths and weaknesses would be such a big part of Doom's legacy, but when he brought up Halo's similarly templated Covenant and Far Cry's pirates and privateers, I started to realize how right he was -- and when he used Far Cry's enemies as an example of poor orthogonal differentiation I found myself disagreeing - I think Far Cry has some of the strongest of this type of design found in modern games, but the reason they don't pop out as strongly as Doom's creatures has more to do with another hugely important aspect of it's design - hit-scan weapons.

The enemies in Doom are easily told apart from another by their weapons, a mix of projectile, hit-scan, and melee. A big aspect of this system is that players are able to dodge melee and projectile attacks but not hit-scan ones, forcing them to prioritize targets, strategize when encountering mixed groups, and reward skilled players by making most damage avoidable. Hit-scan weapons, however, don't allow for the same amount of depth -- enemies can miss and you can use cover, but it's basically impossible to juke hit-scan weapons. While the different enemy types in Far Cry go some distance towards forcing the player to plan out an attack beforehand (especially when attacking outposts), the fact that all of them are equipped with hit-scan weapons makes it much less a test of skill than it may have been otherwise. And it isn't like this type of design is some sort of dirty reminder of some terrible choice - Halo brought it and projectile attacks back and achieved great success, so it definitely seems doable, and Destiny has shown the mix still has potency.

I haven't had a chance to check out Far Cry Primal, but it stands to reason that Ubisoft would stick with the design methodology when it comes to enemies that they've been following to success since Far Cry 3. Since I doubt we'll be seeing projectiles in the franchise anytime soon, I wonder if adopting a simpler approach to enemy design and abilities like what was done in Far Cry 2 might suit the franchise a better.