It's tough to give an exact estimate of the cost that one would incur in developing a mobile game, as it heavily comes down to individual requirements at the end.
However, there are certain factors that are mandatorily applicable in deciding the final cost of your game.
One such factor is your choice of the operating system.
There are certain elements of game development that would cost more if you choose a particular operating system. For example, payment integrations and administrative systems for IOS based devices would come at a 10 to 20% higher cost than that of android.
However, developing a game on android would cost you more if you want your game to be compatible with the older versions of android devices.
Choosing a hybrid model may lead you to incur higher costs that are exclusive for both the platforms, but provide you with a much larger consumer market to gain back your development costs.
Also, the type of game engine that you choose for building your mobile game will affect your cost, although not that significantly.
The second major factor is the level of complexity of your game, and it can be divided into four major categories:
(1) Mini-games: $3000 to $20000
Basic, entry-level games like flappy bird fall under this category. A game with good potential in this category generally requires a minimum budget of $10000, as going below this budget means developing the game under a lot of limitations.
(2) Simple: $20000 to $60000
This is the category that most small budget games fall into. Some popular games include Stack, Hop, Red Ball, etc.
(3) Moderate: $60000 to $120000
This category of games generally has a certain depth in their content, graphics, the storyline, etc. This content depth ensures the wide scope of replayability and a large scale audience appeal.
(4) Complex: $120000 to $250000
Developing games under this category always involves a high risk to reward ratio. These games are generally top-notch when it comes to the content, graphics storyline, etc. The average building time ranges between 1-2 years.
The above graph shows that India and eastern europe hace the cheapest rates, when it comes to building a mobile gaming app, with hourly rates of less than $50.
Game release costs
When it comes to releasing a game on Google's play store, a onetime fee of $25 has to be paid.
However, apple's app store charges $99 yearly for a game release.
Game Maintenance Costs:
The most common costs that you would incur after your game release are:
· Costs for adding new features to your game
· Costs for upgrading to latest OS versions
· Bug fixing costs
Game development companies generally provide you with two models when it comes to game maintenance, namely On-demand that charges you hourly and full time that charges a fixed amount or hourly rates as well.
Other than this, there are some regular default payments that you have to make, such as server hosting costs ($40-$200, annually).
I hope this was helpful.