Embarcadero has four mobile arcade game projects for Delphi in Object Pascal available for free over on GitHub. All of the projects run on Android, IOS, OSX, and Windows. One of the projects is called Space Rocks and I modified this project to allow the player to customize the game at runtime (for more info about Space Rocks check out this blog post). The modified game is called Deep Space Rocks. I also re-skinned the game a but with a new background, player character, and enemy characters.
The new Customize Game functionality that I added to the project allows you to modified the following settings at runtime: Player Image, Enemy Image, Asteroid1 Image, Asteroid2 Image, Asteroid3 Image, Powerup Image, Background Image, Player Health, Collect Item Duration, Collect Item Speed, Rock Speed, Enemy Proj Speed, Enemy Speed, Player Proj Speed, Player Fire Speed, Player Rotation Speed, Player Speed, and Player Lives. This allows the player to tweak the settings and play it how they want to play it. It also allows you to easily play test and tweak the game yourself to get the best settings.
Allowing players to customize your game like this can increase player retention of your game. The player customize-able settings could also be expanded to include more settings like the sound and music. Full source code is provided for this modified version of the game.