In action games, enemy variety is one of the most important aspects of keeping the player interested. However, some games just throw the same 3 enemies at you for the entire length of a 8 hour campaign which makes it incredibly monotonous.
BattlebornBattleborn becomes extremely monotonous because it throws the exact same enemies at you for the entire game. Not only this, but the enemy behaviors are extremely dull. The player will get bored of this design in the first hour or so.
Tom Clancy's The Division
The Division is a great example of having a very bland set of enemies and doing a very poor job of iterating upon them and keeping them interesting throughout the game and expansions. The same enemies the player fights at the beginning of the game are fought at the end, with the only differences being that they have much, much higher HP and damage. With a game centered around shooting things, the player's main obstacle throughout The Division thus sadly and simply becomes to spend more time shooting the same things.
Skyrim's dungeons unanimously struggle from being based on tombs - and the main / only enemy being the undead Draugr. The player is led to a great many of these dungeons in the main quest, in side quests, and via organic exploring. Dungeons are filled with Draugr, and the player will chew through a fantastic number of them - but because of the simplistic combat system, the extremely consistent visual design, and the sheer number of zombies, all of them inevitably blend into a bland continuum. At best Draugr are distinguished from each other by simple spells and extra bits of iron for more important zombies, but they all feel exactly the same in combat as they blindly rush at the player, throwing all their abilities at them until they or the player die. If Skyrim was interested in relying on the Draugr as a consistent enemy race, the game would have benefited from more robust AI and more differentiation between the different classes of Draugr.
Demonstrative Examples Edit
Yaiba: Ninja Gaiden Z Edit
In Yaiba: Ninja Gaiden Z, the player will have fought the entirety of the enemy types the game has to offer by the end of level four. The game only contains seven levels and the player is repeatedly tasked to kill the same zombie enemy types over and over again. The sub-bosses the player encounters consist of large zombie babies, dog-like mechs and helicopters. These fights are thrown at the player every couple of minutes and the only element of variety is the enemy combinations these sub-bosses are latter accompanied with which include the same zombie creatures the player has faced throughout the entirety of the game.