Many modern games introduce a plethora of quests and systems for the player to take part in outside of the main story. This could include mechanics ranging from a shop management system to a breeding system to an item collecting system. These could be included to develop the world the game takes place in, to provide the player with opportunities to obtain extra weapons, armor, experience or money, or simply to hold the player's interest in the game for longer. Many of these systems are optional or unobtrusive: there may be a brief tutorial explaining the mechanics of whatever system the game includes but they are often not mentioned again unless the player chooses to partake.
However, some games will force, or at least heavily emphasize, the player into using a side-mechanic which is unrelated to the story and may be detrimental to the player's progress through the game. This detriment may come in the form of wasted time or even from a handicap to player progress that the mechanic enforces.
Tales of Symphonia: Dawn of the New World is a JRPG focused on dungeon exploration and real-time, party based combat. The party in the battle may include up to four characters aligned with the player against a varying number of enemies. The player controls one of these four characters at a time but can freely switch between characters through the course of the fight. If the character that the player is controlling is killed in the battle, control will automatically switch to another character at which point the player can continue the fight or apply a healing spell or item to their fallen comrades. It is worth noting that if all four characters are killed or otherwise incapacitated in a battle then the player receives a game over and must reload from a previous save.
This game introduces a mechanic of capturing monsters and using them to battle against enemies. The use of this mechanic is introduced in the first dungeon of the game in the form of an unskippable tutorial where the player must either capture a monster or endlessly repeat the battle until they do. At this point, the player has two characters in their party so captured monsters are automatically added into the four person battle party. Aside from filling in slots in the party in the first dungeon, this monster capture mechanic serves no purpose in the game. The player gains more humanoid characters very early in the game, removing the need to fill slots in a four person battle party. Additionally, monsters are almost always much weaker than the humanoid characters and the player is not afforded the option to boost the stats of the monsters with armor or weapons like they are with other characters. The most glaring negative regarding this feature is that the player cannot control monsters in battle. If a party in battle is made up of a mix of humanoid characters and monsters and all of the humanoid characters are killed or incapacitated then the game is over regardless of the state of any surviving player aligned monsters in the battle.
As the game progresses, the player is encouraged to continue utilizing this mechanic either through exposition, forced battles with certain monsters that can be captured, or the introduction of items which makes capturing monsters easier.