If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
In Silent Runner you pilot a submarine, and are sent on missions to clear territories of hostile ships. At your disposal are a large amount of powerful torpedoes, enemy-detecting SONAR, and of course the ability to dive and hide underwater.
Arrow keys – Engine throttle / Steer ship / Turn periscope
Space Bar – Toggle SONAR
Hold Z – Aim torpedo with arrow keys
Release Z – Fire torpedo
C – Ascend
X – Dive
P – Toggle periscope view OR ascend to periscope depth
If you manage to get yourself beached or otherwise stuck you can hold 0 (zero) for five seconds to restart the level.