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.


Examples

Geometry Dash Lite Geometry Dash Lite
"Playing levels can give you keys that open chest that give randomized loot"

Bloons TD 6 Bloons TD 6
"Finishing round 100 gives random insta-monkeys, collection events give random insta-monkeys."

Squad Busters Squad Busters
"Random chest loot and rewards through multiple tracks."

Dragon POW! Dragon POW!
"Armours and Weapons have randomized stats or set bonuses"

Idle Angels Idle Angels
"Competitive rewards are based on your performance, but the battles are always automated. You are technically in control of your lineup order, but nothing else. PvE rewards are random, but predictable depending on what part of your daily operations you're completing. Event rewards tend to be consistent, but based on how far in the event you are able to progress. Most of the PvE events are actually easy."

Hill Climb Racing 2 Hill Climb Racing 2
"You get chests for winning cup races, which give you random rewards."

Solo Leveling:Arise Solo Leveling:Arise
"Typical gacha that uses game/premium currency."

Isekai:Slow Life Isekai:Slow Life
"There is a loooot of random rewards for doing the most basic of tasks. Especially during limited events"

Blue Archive Blue Archive
"Missions, bounties and commisiones can drop certain more useful items at a lower rate. Also the way to get Elephs through hard missions works like that"

My Talking Tom Friends My Talking Tom Friends
"almost everything you do gives you bus tokens (see my review on loot boxes)"