At the end of my first year at university, I created Zommies, a 2D side-scrolling shooter in C++ using DirectX, featuring randomised missions from a base of operations.
One of the main challenges was optimising collision detection. Originally, every object checked for collisions against every other object, which caused serious performance issues given the number of tiles in each level. I addressed this by separating colliders into two arrays: static objects (tiles) and dynamic objects (characters and bullets), greatly improving performance.
I also developed a basic map editor as a separate application, which used the same assets, allowing levels to be created quickly and efficiently. All of the artwork for the game was created by myself using GIMP.
Stefan Yeung 