Listen.. We know you're offering your game for free. And that's nice. We also know you need to make a little money off it so you can keep offering your games for free.. That's okay too.. What's not okay is making ads that interrupt game play or pull players out of the moment. Full screen ads that happen too frequently or flashing banner ads that never go away are not fun. They detract from the game experience and make your game far less enjoyable. A less enjoyable game means players play less. If players play less no one will see your ads and your efforts would have been for naught.
As such, if you intend to monetize your game with ads it's best to place those ads where players will not be distracted from the game. Simple banner ads along the main menu or pause menu are good places. Maybe a one time full screen ad when the game is first launched. These are far better than the banner ad that never goes away, takes up important screen space on small devices, and is constantly flashing at the user "CLICK ME FOR OTHER 'AWESOME' THING". Avoid these at all costs.. because they will likely cost you more than they make money for you.
And remember.. offering a one or two dollar "ad free" version is a nice addition.. but isn't an excuse to use horrible advertising methods in order to coerce users into spending money.. It's more likely they'll just run away from your game.
Demonstrating Example Edit
(This was mostly from experience of looking in the Google Play store for time wasters.. so I had to go look up an appropriate example.)
Take the game Six!. While it uses a banner ad.. this ad is constantly present (even during game play) and is constantly flashing content at the user. Ultimately, this attracts the user's attention from the game itself, thereby reducing the quality of the experience the user has while playing the game.
In the game Quiz Up, you get to play trivia games with friends, but after each game, you have to watch an ad, which can range from 5 sec. to 30 sec. You have to do this after every single game you play! It often takes just as much time to get through the ad's as it does to play a game. They also have a banner ad playing at the bottom of the screen. The content, unavoidable bombardment of ad's have destroyed the game for many users.
The thing isn't mobile strikes itself has too much ads, the thing is its ads are everywhere in other games(I couldn't remember which specific games have its ads, but I just think it's so annoying)
This game has a very good story and gameplay where you play as an animal and try to escape the Zoo by sliding over a gigantic skyscraper while dodging projectiles and collecting food. It has an excellent 2D visuals using pixel art form and the view is shown from a side-on perspective. The game has the quality to make at least a million download but it has just seen five thousand download in the Android store with little reviews. All the good layers of the game is abstracted by the blocking advertisement. In my observation, I found popping advertisements everywhere(landing page, gameplay). This frustrated me and I developed a negative feel towards the game. The game creators gives an option to get a paid version for which they claim there will be zero advertisements. But the choice of advertisements in the free version didn't attract me to go for the paid version. It would have been wiser if the In-Game advertisements was used in a humble manner which made me to participate rather getting frustrated.
Hears has too many ads.
1010 is a free mobile puzzle game where you must fill an empty grid with shapes. The game ends when you’re unable to place a given shape on the grid. Simple as that sounds, the game chooses the worst time to display ads. One such instance is when the game ends: the game freezes (presumably to fetch the ad over network), after which the ad is displayed and on closing the ad, the game finally plays the level complete animation and game over screen.