The calculator I made for Kerbal Space Program used values from the game’s wiki, including: mass of planets, size of their sphere of influence and radius. Using these and some basic physics, the phase angle (the angle from one planet to another) was calculated. Allowing users to perform a Hohmann Transfer orbit between location and destination, using the minimum delta-v.
I developed a bespoke multi-stage plain text encryption system. Here characters are converted into ASCII numbers before reversible mathematical operations are performed on the text. As long as two users know the key, they can encrypt, send and decrypt secret messages.
To speed classification of human neoplasms, I developed an OpenCV program to calculate the proliferation index of cells in a medical image. In a three step process of filtering, segmentation and then counting, the program could quickly and accurately tell the user if a tumour was likely malignant or benign.