Teppoman is a pretty cool game, and definitely entertaining. Basically, what you do is pick up guns and free the hostages. There are different guns to pick up, and the levels get harder and harder. Be sure to get all of the hostages, or you won't get to do all of the levels.
The enemies are easy to kill at first, but in the harder levels there are more of them and they are positioned in hard-to-reach places. That makes it very difficult to reach and kill them before they kill you. Really fun game, good sound effects, and ok music. Don't expect the latest graphics and visual effects. But you can expect a well-built Mario-type game that will provide you with hours of fun.
Note: There are no manuals, but the controls are simple: arrow keys for movement, shift for jumping, ctrl for shooting (or punch if you have no gun), down arrow for freeing hostages, and up arrow for climbing on the green nets.