Why are mobile games so full of ads?
The most important reason is that ads allow developers to make money from free games. Apps take time and money to develop, so most people that create them want to earn an income from their work, or at least have the money to maintain the app.
Why do games show ads?
In-game advertising is a monetization strategy that game developers use to boost their game's revenue. Game developers earn money and get paid by showing mobile game ads to their users. 73% of gamers are happy with the ad-based model of games today.