Crosslib by Fabrizio Caruso is a retro-hardware abstraction layer library to program on retro computers without bothering about the particular hardware. You can program on many many platforms including the Amstrad CPC, and also it seems (by reading the release/tags) the Amstrad Notepad NC100 !

He wrote two gamse with this library as examples :

• Cross Chase (2017), stated as slow
• Cross Shoot (2020)

I tried Cross Shoot and after several attempts I was able to finish level 1. Well please read the rules of the game to avoid wasting time like me : the goal is to kill all common enemies or kill all 4 "skulls". Common enemies can be killed quickly if pushed against the walls by shooting at them. The "skulls" and the boss cannot be pushed and are harder to kill. You have to avoid all enemies, all walls, rockets and chasing missiles. All flashing items have positive effects and can grant you special powers. Your bullets have a limited power that can be improved by catching the multiple times special fire power item. You can also fetch the mine item that grants you 3 powerful mines to use against all your enemies. Discover the 11 items. Some items are secret. In total the game has 12 secrets. You can unlock the 12 secrets by shooting at the skulls and at the missile and rocket bases in different ways. The game has 16 different levels including 2 boss levels.