This "time pod" runs into trouble, sustains damage and needs to be repaired. Thus in each level, you need to snatch up one of your missing "time circuits" so your gizmo can eventually be repaired. Unfortunately for your robot, the levels are designed in a way that makes it impossible for you to collect the pieces on your own. However, since your time pod is still semi-functional, you can just go back in time to help yourself.
While it's true that time travel or a "rewind" concept isn't necessarily cutting-edge anymore when it comes to casual games, the concept is refinedand executed almost to perfectionin Chronotron. First off, the controls couldn't be simpler. Move, crouch and jump with either the [arrow] keys (or the [WASD] configuration), and use [space] to interact with your time machine. Traveling back in time is the key to completing each level, since the levels are designed to require two, three or four (and even more) copies of yourself to work in unison, collectively allowing you to reach your goal and return to your machine. For example, in the first level, your circuit board is on a platform that's too high for you to reach. There's a pad nearby that you can stand on, which raises an elevator, allowing you to reach the circuit. However, the second you step off the pad, the elevator lowers back down. Hence, you need someone to stand on it for you. Why not yourself? Just stand on the pad for a few seconds, then go back and enter your time pod. A duplicate copy of yourself pops out, mimicking your previous actions exactly. Since the "previous you" is standing on the pad, the "current you" (always marked by a green arrow above your head) is free to hop on the elevator and retrieve the circuit board.