The promissing part is: at last a variation of the domino game that really could be compelling and fun for quite a while.
The disappointing parts are:
1. Akward user interface and controls: buttons/controls need to be tapped multiple times to make them react/function (sucks). Design and user interface implementation seems technically week and outdated (e.g. need to switch to a seperate full screen display to select piece/s to play, requiring a (lengthy) sequence of taps instead of overlay technique).
2. Graphics are rather poor. Considered the relatively simple graphical objects (background, domino pieces, trains) this seems outright stupid.
3. There are instructions on how to play the game. But with rather week explanations of everything and even leaving some details to the player to figure out.
4. This is a trial version, allowing only to play a smaller part of a game session (3 out of 13 rounds)! Not even a whole game session, a single time! And considering the bad quality of this title, it's just rude to NOT offering this game for totally free. You will have to make an IAP to unlock the full version of the game. Provided anybody at all will be stupid enough, to do so!
Hence the conclusion is: IMPROVE (considerably!) OR PERISH! Alterative: make it totally free.