I liked how this came out, although I felt that at the same time there were some issues that made the game somewhat look unpolished or incomplete, especially considering there is a paid copy:
-Some features are missing compared to the TI-83+ original. For example, the background in Level 3 and 9 should normally scroll by itself (backwards in LV 9) or be animated to act like it's scrolling. The animations speed are sometimes wrong too.
-Although on the PC it's fine, on my Nexus 5 the frame rate is extremely choppy. I'm unsure if much can be done about it due to the language limitations, though, but I suspect that you are rendering the entire map every frame rather than only what's visible.
-We can change the resolution as we see fit, which gives an unfair gaming advantage to people playing in full screen mode. I think that instead, the game should scale itself up (using no smoothening filtering on the sprites) so that it always remains a 20x15 sprite grid in 4:3 or 27x15 in 16:9.
-Since there is music, maybe some bouncing or hit sound effects could be added.
-Also the highscore list no longer works.
-The title screen logo animation is missing