Let’s talk about depth. In terms of game design, the basic goal is usually the same. The player is trying to accomplish some goal and obstacles challenge the player’s achievement of that goal. The player then uses inputs at their disposal to overcome those obstacles and get to the goal. Many games have simple “enemies” as obstacles, but this varies with the game and its genre. In terms of the player’s toolkit, that’ll be whatever the controller or keyboard buttons are bound to, including movement and attacking in many games.
These obstacles and tools aren’t what make a game entertaining on their own, however. One key factor in that variable is how many valid options the player has to overcome the obstacles given. If there’s only one “right” answer to get past every obstacle the satisfaction will be short-lived as repetitiveness kicks in; the decision isn’t interesting as the player doesn’t have much say in it. Interesting decisions are the ones in which the answer isn’t obvious, such as what character to pick in a (well balanced) fighting game or what loadout to use in a shooter. Some decisions that do have obvious “right” answers can still be entertaining because they rely on prior decisions and therefore still matter at their roots. A game with lots of interesting decisions is known to have high amounts of depth.
Depth is one of the keys to making a long-lasting game, as it determines what the skill cap of the game is. Games with high amounts of depth often play out very differently every session since decisions matter greatly and the opponents might also make their own decisions that influence yours. This depth is also what frequently is the determining factor for a game’s complexity. This isn’t always true, such as with the board game Go and its simple ruleset yet extreme depth, but they’re typically correlated. Some of the “worst” games are the games in which there’s extremely complex rulesets but very little depth due to dice rolling or some other random mechanic. They can be entertaining every once in awhile but most people usually won’t want to play them extensively due to the extremely low skill cap.
On the other game, complex games with lots of depth can often be intimidating and tough to learn for a newcomer. You can see this in many games that are popular today such as DOTA 2, League of Legends, or most competitive multiplayer games. Accessibility often conflicts with depth, but there are ways to handle this conflict. The most common way is through having a super strong onboarding experience such as an in-depth tutorial or keeping your complexity down to make things easier to learn. Alternatively, a developer can ignore the problem and simply cater to the appropriate audience; games like DOTA 2 are well-suited for hardcore gamers that are willing to commit to the game and overcome its learning curve, whereas many popular mobile games like candy crush or most of the various city-builders are often meant for casual players and have simple objectives and relatively low depth as a result.
Important Takeaways: All games have the same basic objective: Accomplish a goal and overcome obstacles along the way. The amount of meaningful decisions in the game will determine a game’s depth, and complexity is often correlated with depth. Higher depth in a game is usually a good thing, but the complexity that can come with it can ruin the appeal to new players. If the game has high complexity, its accessibility tends to be poor without a proper onboarding experience, so you can either attempt to guide new players through the complexity with a strong tutorial, reduce the complexity as a whole, or gradually introduce players to increasing complexity (the best option).
Alternatively, you can make a game that caters to a niche audience and have the best of both worlds. Games like DOTA 2 are built around hardcore gamers that are willing to dedicate significant amounts of time to a single game, so the game’s incredibly high depth and complexity has barely been touched except in cases of making things intuitive. Games like League of Legends has a progression mechanic that gradually ramps up the game’s complexity, so that new players don’t feel too overwhelmed. Conversely, many mobile games are often examples of games built for a casual audience that doesn’t necessarily want something that has high depth and complexity, but something that provides ample rewards for relatively simple gameplay.
In order to properly design games with suitable depth for extensive replayability, both the onboarding process and the core progression system must both lead towards ever-increasing complexity, resulting in a game that has an increasing skill ceiling that positively correlates with play time. Easier said than done? Absolutely. That’s why experienced game designers aren’t going out of style any time soon.