While recently re-examining the Google Play Store policies, we took another look at the rules against keyword spam and what the company suggests for app descriptions. Developers are advised to stay away from classic spam techniques like repetitive keywords, exceedingly long descriptions, and unrelated keywords or references. Publishers will often use these tactics in an attempt to sneak their apps into unrelated search results. One of the most interesting of these recommendations comes at the tail end of the page where Google advises against referencing other apps you've published.

Excessive detail, references to your other apps Your app description should avoid excessive detail and references to your other apps or products. For example, you should not list all of the details of content included in the app or its various components, as shown in the example below. Also, the description should not include any references to other apps you’ve published.

The explanation is followed by this example:

If you like this app try our other free apps:

★ Fun Zoo

★ CD Guns

★ Dessert House

★ Playground

★ 578 Weapons

This policy is obviously there to prevent developers with multiple titles in their portfolio from gaining an unfair advantage or inflating search results. Historically, this practice has been heavily abused by game publishers, but also shows up with many utility apps. While it's not spelled out, this rule probably doesn't apply to edge cases like game sequels, unlock keys, plugins, or apps with tight feature integration (eg. a news app that can repost to Twitter and Facebook).

Given how easy it is to find examples of this practice, it's likely most developers don't even realize they have been violating this policy. Some larger game studios, like Gameloft and Glue, have already changed their app descriptions to reflect this rule. However, there are still plenty of offenders, including everybody's favorite: King. The prolific trademark owner, and maker of Candy Crush Saga, mentions its runaway hit in 4 out of 5 games on the Play Store (Note: 1 of those is the game itself).

It's not clear if Google is actively enforcing this policy or if its presence is simply a warning to potential offenders. Nonetheless, it might be a good time to tidy up some descriptions. If your app gets removed, don't say we didn't warn you.

Source: Play Store Policy Guidelines and Practices