Finding the balance of how difficult a game needs to be in order to keep the player engaged can be very hard as a designer. One thing a designer can do in games is make their players decisions meaningful and have consequence. This makes the player understand that what they are doing matters. A consequence mechanic can give the player a sense of ownership of the game. Some designers go to far and make the consequence to great. Permanent death or loss of an item can be to much for the player to handle. In most cases a player will roll back on a save when they have done something that has resulted badly for them. This type of thing has to be counter to what the designer had in mind.
Examples:[]
Ghost Recon[]
In some of the earlier ghost recons players are enticed to play mission on higher difficultly so that they can unlock special characters. These characters are heroes from current and past wars. Each hero has special traits and are buffed higher then common heroes. If the player chooses to play as one of these heroes and then dies that hero that they spent time to unlock is gone from the game. Permanent death for a reward item/character in a game is too harsh. This makes the player not want to play as the new character they just got for fear of losing them.
Pixel Dungeon[]
Pixel Dungeon is a rogue-like game in the same vein as Nethack. It is a dungeon exploration game which forces players to progress through a series of ever-more-difficult levels to reach the bottom dungeon and claim victory. While doing this, players level up and acquire new items and accessories to help them in their quest. The game is designed to be difficult, and the difficulty of rogue-like games such as this is understood. Sadly, this difficulty can quickly turn casual players away from trying the game beyond a couple playthroughs. The game is very hard. If you die, you die. There are no saves, do overs, or repeats. You must start a new game as a new character every time, no matter how far you progressed. The fact that you will die and die often is actually expected for those who play such games, but it is not immediately obvious to a new player, and can cause frustration and avoidance of the game entirely.