Variable Rewards
Unpredictable or random rewards are more addictive than a predictable schedule.
Casinos know that slot machines are more addictive if they pay out a random reward at unpredictable times. If people always won back 80% of their money on each pull of the lever, it wouldn't be an exciting game and wouldn't be addictive. It's the unpredictable and random nature of the rewards that keeps people playing with the hope for that rare big jackpot.
A constant or predictable schedule of rewards is not very exciting. This is why games often randomize the rewards that you receive for finishing a level or defeating an enemy. By making the rewards like a slot machine, they are trying to make the game more additive. They may also be trying to extend gameplay by making you grind longer to get what you want. If you need a certain item, but it only appears as a reward 5% of the time, people will keep playing over and over with the hope of getting that rare item. If the game has limited energy and forces you to wait to play then people may end up paying money to skip the wait.
A constant or predictable schedule of rewards is not very exciting. This is why games often randomize the rewards that you receive for finishing a level or defeating an enemy. By making the rewards like a slot machine, they are trying to make the game more additive. They may also be trying to extend gameplay by making you grind longer to get what you want. If you need a certain item, but it only appears as a reward 5% of the time, people will keep playing over and over with the hope of getting that rare item. If the game has limited energy and forces you to wait to play then people may end up paying money to skip the wait.
Citations and Sources • Why are Video Games Addictive?
• Behavioral Game Design
• 5 Game Mechanics that Make Games Addicting
• Wikipedia :: Reinforcement
• Behavioral Game Design
• 5 Game Mechanics that Make Games Addicting
• Wikipedia :: Reinforcement
Examples
Mario Kart Tour"The pipes are random rewards. If you come back daily, you also get a Daily Reward, but those are already predetermined and visible."
Harry Potter: Wizards Unite"The appearance of rare Foundables is pretty rare and variable."
Star Trek Fleet Command"There are free loot boxes that give you very little at all, and if you get anything of value it is almost always the least amount listed in the chances."
Dragon Champions"Randomly selected raid and tournament rewards."
Gems of War - Match 3 RPG"When you complete any puzzle, what you get from that puzzle is luck based."
RAID: Shadow Legends"Shard mechanics"
Fate/Grand Order (English)"%chance of specific loot dropping for clearing different missions."
Walking Dead: Road to Survival"From end of stages or end of war matches."
Crossy Road"Characters are rewarded through a 'capsule machine', which can provide duplicates."
Roblox"As Rōblox is a platform of games (rather than a single game in itself), developers are allowed to do just that. If the title of the game you're playing ends with 'Simulator', you're definitely in one that does."