I have made a scroller game where player moves to the right of the screen. I add a new uniform ground block about every 5 seconds.

I was wondering how often should I put bonus items. Currently I put them with 0.5 chance per added block of ground and if I fail to do, I do another 0.5 as a secondary chance. Once the player has enough number of items, then she can buy skins.

Is there a well known item distribution algorithm or a resource I can benefit from? I only have 1 type of item to keep it simple and the game is for mobile, but sounds like those items shouldn't be rare.


The frequency of bonus items would mostly affect the time players spend to acquire the necessary amount and buy a new skin. So, it comes down to the cost of the skins, the movement speed and the percentage of all bonus items players manage to collect. You can get a rough estimate of the time spent on buying one skin by calculating it from these variables.

The more often the players encounter the items, the less time they need to buy a new skin.

Or just run several playtests and measure how long it takes. This is also more precise and takes into account all the variables (including level design, which can be hard to incorporate into a formula). It is up to you to decide how much playtime buying the skins should take — better ones would require more time, you get the point.

  • \$\begingroup\$ I agree time between perks is a good measure, so makes sense. \$\endgroup\$ – morevitamins Sep 1 '17 at 19:16

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