Don't Forget Fun

A while ago I played through Darksiders, a beat-em-up where you play the role of "War", one of the four horsemen of the apocalypse. Now, while the writing most definitely fell into the mediocre category, the game on the whole was quite fun.  However, there were design aspects that meant the game fell far short of what it could have been.

Part of the problem with Darksiders is that it cobbles together a whole bunch of ideas from different games.  Platforming and puzzles have become standards in the modern beat-em-up, and the Prince of Persia series was great for mixing these aspects together with beat-em-up combat.  Darksiders does okay in this regard, but its shortcoming is that the game is schizophrenic in its presentation and design.  You have completely new abilities and mechanics dumped upon you as the game progresses, but few of these mesh well together. You get a gun, then a horse, then a grappling hook, then a portal gun, then "see invisible" mask, and a few other goodies besides. All these things might be interesting in their own regard, but they simply don't work well together and force you to engage with new mechanics which are used for a period and then largely abandoned.

Copying portal was out of place, and generally not a good idea

Worse still, some of these mechanics become tedious.  Playing portal in Darksiders for the most part requires little thought or puzzle solving, for all the portal locations are predetermined, leaving the player with few possible options to solve a problem.  Worse, the game counter-intuitively has the mechanic such that it is possible to shoot a new portal through an existing portal, yet at no point is this actually explained to the player, which resulted in many players engaging in intentional suicide/respawn patterns in order to establish a portal in what seemed like an otherwise unreachable location. Movement mechanics and particularly the "see invisible" mechanic led to backtracking that added very little to the game except extended playtime.

Players should not need to come to the same location over and over again

This was one of the contributing factors to the game's main problem: it stopped being fun. The backtracking of the game meant players were going over old territory repeatedly, but even worse, they were dealing with enemies that became increasingly less fun to fight. This was through the introduction of single enemies that could deal a large amounts of damage and required a largely defensive strategy in order to defeat. Considering much of the fun of the combat of the game (as with many/most beat-em-ups) is the challenge and skill involved with stringing together combos in order to defeat a large group of enemies.  Staged boss fights are the icing on the cake, but the bread and butter is the defeat of enemy hordes - a recipe that the Dynasty Warrior series understands implicitly, as that is the entire point of the game.

As the game progressed, the introduction of enemies such as Wraiths, Grappleclaws and Undead Shield Lords forced the player into more defensive fighting strategies, undermining the fun of the fighting activities the player had experienced early in the game.  As Darksiders continued, its combat became less fun, and its gameplay more repetitive.  Darksiders is one of those rare cases where it would have been much better if the game had ended half a dozen hours earlier. A shorter game would have cut out the additional repetition introduced by the tail end, not to mention the more tedious fighting sequences in the game. While it's an enjoyable romp, Darksiders will ultimately leave you feeling a bit irritated by the time you reach the end because of these shortcomings, and the fact that the boss fights become progressively easier until the fight battle feels wholeheartedly underwhelming.

These were dull and annoying to fight

The take home lesson from Darksiders is to not forget what makes your game fun.  Good design is not about trying to pack as many different mechanics into a single game as possible, even if you're taking them from games that are very popular. It's not about making the game as long as possible if it's at the expense of the quality of the gameplay

Focus on one gameplay mechanic within a game (probably three at most) and make sure it is fun and has depth in order to make your game as enjoyable as possible.  Try to make a gameplay mechanic easy to pick up, but difficult to master. Make it possible for the player to succeed, but if they wish to succeed at a higher degree of difficulty or earn some recognition of increased skill from the game (e.g. via a points system), they will have to learn and practice mastering the mechanic.

Make your primary mechanic fun and make sure the player can enjoy it for the entire length of the game, and you will have avoided the mistake that Darksiders makes.