Power Creep
A permanently purchased item in the game becomes less valuable over time.
Power creep is a term used to describe a situation where an item in a game depreciates in value over time. The main way this happens is via new content being added to the game that make the old content less valuable.
The idea is that you may have earned or paid for a powerful item or upgrade in the game. It may have been great for awhile, but new better items are available or the power level of the opponents has increased to the point where that original item is no longer useful. The money and time that you previously spent to earn that item is now worthless and you must spend more money and time on the new more powerful item to have the same benefit that you had before.
If games do this often, it encourages players to keep spending money to stay competitive. If done incorrectly by the game developer, it also has the effect of making the game boring for new players who start with the new powerful items which are overpowered against the opponents found in the beginning of the game. The original game can become unbalanced if too many updates are made that keep adding more and more powerful items.
The idea is that you may have earned or paid for a powerful item or upgrade in the game. It may have been great for awhile, but new better items are available or the power level of the opponents has increased to the point where that original item is no longer useful. The money and time that you previously spent to earn that item is now worthless and you must spend more money and time on the new more powerful item to have the same benefit that you had before.
If games do this often, it encourages players to keep spending money to stay competitive. If done incorrectly by the game developer, it also has the effect of making the game boring for new players who start with the new powerful items which are overpowered against the opponents found in the beginning of the game. The original game can become unbalanced if too many updates are made that keep adding more and more powerful items.
Examples
Star Stable Online"horses from previous generations will eventually be removed from the game and are significantly worse than newer horse models."
Cookie Run: Kingdom"meta changes a lot in the arena, and some cookies just... become less useful as you progress."
Cursed Treasure 2"Things purchased with the in-game currency (which can be bought via microtransactions) only last until the end of the level. The amount of in-game currency remains between levels."
SUITSME: Dress Up Fashion Game"Clothes get worn after the first time they are used, so you'll need to either buy new stuff or repay to renew the item."
IdleOn - Idle MMO"New updates will nerf older items"
Figure Fantasy"Yes,things you buy to spend on current figures will be usless as time goes on as most of thise figures themselves will become unusable when new figures gets introduced, also the game is shortening the time between new characters release, recently they removed the concept of one week brakes between new figures banners shortening the time for multiple types of preparations and causing resource,growth,loss while also hastening previously released figures exploration."
Empires & Puzzles: RPG Quest"I wish I had found this site when I first started playing the game. Vehemently."
Love Live!School idol festival"Newer cards tend to have more powerful skills."
Mighty DOOM"You badly need to upgrade equipment to win against difficulty spikes."
Idle Cake Tycoon - Hamster Bakery Simulator"you need more and more of certain items"