There is no need to use a return PLUGIN_X inside of plugin_init, unless you don't want your plugin to work or in a restricted mode. In which case you can just use return
inside of your statement. This way you don't need to add an extra return at the end of plugin_init.
register_plugin( PLUGIN, VERSION, AUTHOR )
if ( !cstrike_running() )
log_message( "%s - error: failed to load plugin ( Counter-Strike Only! )", PLUGIN )
// REST OF YOUR CODE/FUNCTIONALITY HERE