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

Last Fortress Last Fortress
"Yes because if you don’t buy a car or gear or a hero, you will be very weak compared to other players. You “have” to have this item to be competitive and have value"

Minesweeper Puzzle Bomb Minesweeper Puzzle Bomb
"Subscription page keeps popping up"

Automatoys Automatoys
"After three levels, there is a two-dollar paywall to access the rest of the game."

BADLAND BADLAND
"Levels are locked behind premium"

Really Bad Chess Really Bad Chess
"Have to pay for local vs mode"

Drifto Drifto
"There are three cars in the game that require the player to spend real world money to use. Two are $1.99, one is $4.99, meaning if you want to collect every car in the game, you must spend $8.97. While the $1.99 cars are comparable to the free cars, the $4.99 car is an absolute monster with the highest acceleration in the game and a decent top speed to boot."

Peridot Peridot
"CANNOT breed more Peridots without buying nests, and nests all cost money. Once you have used a nest for a Peridot you need another to breed again."

Horizon Chase - World Tour Horizon Chase - World Tour
"Can play 30 races free before a paywall"

Everlife Everlife
"Few cards from this game are under paid packs."

Cursed Treasure 2 Cursed Treasure 2
"The last three levels are a mobile-only addition to the game and their difficulty is notably, deliberately ramped up far past the rest of the game, necessitating use of in-game currency to perfect or even complete the levels."