STift is a poor man's Zwift. Zwift is a popular (subscription based) app for indoor cycle training. It's rather expensive, has far too many features and is not available for Atari ST. STift is an attempt to create a simple and very limited indoor cycle training app for Atari ST and compatibles.
STift lets you do workouts on any indoor bike. Basically, all you need is a heart rate monitor. Workouts are based on your heart rate zones. You can watch your performance and progress during the workout on your Atari screen.
Heart rate zones? Yes, if Atari is good enough then 1980s training science will do just fine. Nowadays it's all about power meters, watts and functional treshold power, but we don't care about that. Your heart rate is a perfect indicator for the power you produce.