Pay Wall

The game becomes impossible to continue playing without payment.

A Pay Wall is a point in the game where you must pay money to continue playing the game. If the game makes this clear ahead of time, then this isn't a Dark Pattern. Perhaps the first 5 levels were a free trial to see if you like the game and then you can purchase the rest. This is essentially the "Shareware" model of game development which is not a dark pattern. A similar practice is Downloadable Content (DLC). With a DLC, you purchase additional content that extends the standard game that you already have. If the DLCs are known ahead of time, this is a clean practice.

It becomes a Dark Pattern when the game doesn't disclose this ahead of time and surprises you with this information after you have been playing for some time. If you have played part of the game already, it may have some endowed value for you, or you may have a partially completed goal that you want to finish. If the game suddenly stops working until you pay to unlock the complete game, you may have a strong incentive to pay. To avoid this dark pattern, games should be up-front about the cost and how much you can pay for free.

A game may also contain a secret hidden Pay Wall. This occurs when the entire game is free, but the difficulty increases steadily until it's nearly impossible to continue without purchasing in-game items or upgrades that make it possible overcome a particularly difficult level or obstacle. The game doesn't directly prompt players for payment, but instead relies on their growing frustration with being unable to beat a level to drive sales of in-app purchases of upgrades.


Examples

Cat Game - The Cats Collector! Cat Game - The Cats Collector!
"When you run out of items a pop up appears prompting you to buy more."

Mystic Messenger Mystic Messenger
"Later routes (particularly Another Story) cost more hourglasses than the player is likely to receive through gameplay alone."

The Ssum : Forbidden Lab The Ssum : Forbidden Lab
"At one point in the game, the cgs that the characters send don't load any longer unless you pay for the subscription and "upgrade" the antennae. it doesn't keep you from making choices in the game, but it does force you to choose blindly since you can't see the photos anymore."

Smash Hit Smash Hit
"It's not a surprise, but there is a pay wall."

Baseball Superstars 2020 Baseball Superstars 2020
"either grind a long time for daily diamonds or pay to get better trainers to fight higher level people"

Destiny 2 Companion Destiny 2 Companion
"The Crucible. Destiny's PVP equivalent for Casual and Ranked play are gated behind Whatever current expansion is in an attempt to curb cheating and exploitation. A $10USD Dungeon key bars players from access when Dungeon were once expected Free."

Cytus II Cytus II
"Some characters have secret things locked behind a paywall, such as the song Floor of Lava"

Fer.al Fer.al
"Re: my point about "Pay to win"."

Star Stable Online Star Stable Online
"The game will only allow you a limited number of quests and areas to unlock unless you buy a “Star Rider” membership."

Kick The Buddy Remastered Kick The Buddy Remastered
"Tons of invasive popups"