Energy
A level that eats five hearts in a row should offer a helping hand, once
Players who lose the same level again and again quit the game, but a help that appears too early or too often cheapens every win. Here is a counter that offers help at the right moment, ignores walking away, and starts over after a win.
A lucky bonus tap changes when the player closes and reopens the game
Tap games hand out occasional lucky hits. If the luck is drawn fresh each time, players learn to quit and reopen until they win. Here is how to make the outcome depend on a saved counter instead, with a guarantee after a dry spell.
Free lunch and dinner energy that can be claimed once per window, even past midnight
Some casual games hand out a free energy gift twice a day in set windows. The tricky parts are the window that crosses midnight, the player who claims twice at the edge, and missed windows that must not pile up. Here is the check.
A limit of three mistakes in a number puzzle punishes the same wrong guess twice
Mistake counters make puzzles tense, but they feel unfair when erasing and retrying the same wrong number costs again, or when scribbled notes count. Here is the counting rule and the decision it hides, spelled out.
Energy that would be lost on a full bar can wait in a reserve and flow back
Casual players hate watching the bar waste its refill while they are at work. A small reserve behind the bar can catch the overflow and top the bar up when room appears. Here is the exact flow and what is still lost.
Picking up a second power-up should build on the first, not cut the bonus off at once
Collectible boosts in runners and arcade puzzles either restart, add up without limit or end in a single moment and feel harsh. Here is a staircase that grows with pickups and steps down one level at a time, with exact timings.
Leaving a level by accident or after a crash should not always cost a heart
Players tap Play by mistake, the app dies, or the level fails to load. Some of those deserve their heart back and some are people dodging a loss. Here is a rule that tells them apart and caps the generosity.
Buying hearts with gems gets pricey, and buying one at a time must not be cheaper
A price that rises with every purchase can be beaten by buying in tiny pieces, or it punishes someone who only needed one heart. Here is a pricing rule that comes out the same however the player splits the purchase, and when it starts over.
A faster refill for subscribers should not hand out a free heart or erase waiting
When a player gets a quicker refill, the half-finished wait for the next heart has to be carried over sensibly. Done carelessly, they either get a heart out of nowhere or lose the time they already waited. Here is the bookkeeping that avoids both.
Speed-up tokens get wasted when a big one is used on a few seconds left
Players own a pile of small and large time-savers and a timer with a bit left. Picking the biggest first throws value away. Here is how to choose the combination that finishes the timer with the least waste and the fewest tokens.
A streak shield that saves one missed day must also handle two, and a clock gone backwards
Daily streaks make people come back, and a shield that forgives a missed day makes them forgive the game. The fine print is what to do with longer gaps, when shields are earned, and what a weird date does. Here is the whole rule.
"Sweep 10 times" with energy for only 7 runs either fails or silently overpays
Skipping through an already beaten level several times at once is limited by energy, by a daily allowance and by the number the player asked for. Here is how to decide what really runs, say why it stopped, and what is missing for the rest.