If you want to develop a game that is really cross-platform, B4A is not the best choice. Nowadays, you have many game engines completely free like Unity or based on a fair agreement like Unreal Engine (they earn 5% of your sales only after your earnings go over a certain threshold). You develop only once and can compile for a broad variety of platforms (not only iOS, Android and Windows Phone, but also Windows on desktop, PlayStation, XBox, Wii, BlackBerry...). You benefit from an API specifically made for games and a bunch a tools dedicated to the specific needs of game development. You don't have to develop your own physics engine or navigation engine, and everything is already optimized. Unity, for example, has a visual scene editor that helps a lot to build quickly your game, a scripting language that is simple to learn, an API that is rich and well documented, an asset store that is well-supplied with top FX or models for your game, etc. What you lose by learning how to use it is quickly regained by all this code you don't have to write, all these things you don't have to manage or worry about...
So doing things with only the core libraries of B4A is probably satisfying for the mind, to learn a few things and test your skills, but to make games, it's a strange decision to my eyes. And the average phone is probably a lot less powerful than a Samsung S5, so without succesful tries on low-cost phones and tablets, you're probably aiming a specific target.
