Commander Keen

You control Billy Blaze, a kid in a homemade helmet, running and jumping across alien landscapes. The goal is to navigate each level from start to finish. You collect keycards to open doors, blast aliens with your ray gun, and use a pogo stick for higher jumps. The pacing is quick, and the levels demand careful timing to avoid enemies and pits. It feels like a precise, sometimes unforgiving, test of your reflexes.