Did some reading, a few to choose from, construct 2, GameMaker, RPG maker VX, Unreal Engine, Unity, Project Anarchy.

My experience, I did programming in C, C#, Java. not familiar with C++, but not afraid to use it. I have tried building Tetris using Irrlicht Engine, load sprite, rotate, didn't work on wall kicking and gravity stuff yet. I have also tried building a shooting game with Corona, learn LUA, don't like scripting language, I would rather use C++.

This time, I want to pick the right framework, and get to the end of a very simple game, 2D RPG, no physics needed. no level editor needed.

I thing I only need basic stuff like game menu, 2D graphics, animation, sound, control. I prefer programming language, no scripting. Targeting mobile platform, Android and iOS.

which engine would be easiest to work/learn and not over kill?

Construct 2, GameSalad, libgdx, didn't try yet, I heard that there are good. how do they compare to each other?

GameMaker, RPG maker VX, only know their names.

Unreal Engine, powerful engine, 3D, affordable license, will it be too difficult to learn? and overkill for simple game?

Unity, another powerful engine, but I heard that it is quite expensive.

Project Anarchy, does anyone heard of this? It is free version of Havoc, I think. I installed it and that takes me hours, could be powerful.

Citrus engine, does anyone heard of this? free and open source.

XNA, I am experience on C#, but does XNA good for mobile game?

thank you for your take on this.

And just to make things more interesting, there are even more popular engines in the Mobile forum FAQ.

Unity and Unreal are not expensive until you start making money, and then your investment is a fairly small amount compared to whatever revenue you earn.

Really every engine, every tool, they all have their own style, their own feel, their own list of pros and cons. For a tetris style game of falling 2d blocks probably some of the 2D engines will work, as would the 2D graphics libraries that are not engines.

I don't really have much experience with most of those you listed to say if they are particularly suited (except perhaps Unity, which could handle it with the 2D systems although tetris isn't a perfect fit), but the ones in the FAQ link are fairly popular.

I prefer programming language, no scripting.

That rules out Construct 2, GameSalad, GameMaker and RPG Maker then.

I would also rule out Unreal, Unity and Anarchy. They will do what you want but also do a lot of other stuff and may be a little more complicated than you need.

XNA isn't really good for mobile games. You need to look up monogame which is its spiritual successor if you want to go this route.

That leaves you with libgdx and Citrus (from your original list). Both a pretty easy to get started with and have comprehensive tutorials to get you up and running in a couple of hours.

libgdx uses Java and Citrus uses an Actionscript like language.

There are a whole slew of other cross platform mobile engines that would also do the job. Some of them mentioned in the FAQ that from pointed out.

You also don't mention which mobile platforms you intend to develop for as some engines even though they are cross platform are more suited to particular development environments.

I prefer programming language, no scripting.

That rules out Construct 2, GameSalad, GameMaker and RPG Maker then.

I would also rule out Unreal, Unity and Anarchy. They will do what you want but also do a lot of other stuff and may be a little more complicated than you need.

XNA isn't really good for mobile games. You need to look up monogame which is its spiritual successor if you want to go this route.

That leaves you with libgdx and Citrus (from your original list). Both a pretty easy to get started with and have comprehensive tutorials to get you up and running in a couple of hours.

libgdx uses Java and Citrus uses an Actionscript like language.

There are a whole slew of other cross platform mobile engines that would also do the job. Some of them mentioned in the FAQ that from pointed out.

You also don't mention which mobile platforms you intend to develop for as some engines even though they are cross platform are more suited to particular development environments.

Buster ! big thank you, you are a life saver.

If target iOS do not need any objectiveC, I would save iOS will always be priority number 1. at least cross platform android and iOS.

the thing is that, Android is not very good for selling game, the only good way to survive for android is In-App-Purchase which is something I don't really like as a gamer.

I think the best way for me to test whether if I could create a valuable game is to sell it at $0.99.

Will try libgdx, I have read the FAQ, but could comprehend very well which one of those fit my requirements.