Start(InitialTime)

Executes the particle generation.

Параметры:

InitialTime

The period of time to "fast-forward" the particle generation before the particles are first displayed (in milliseconds)

Возвращаемое значение:

Returns true if the method succeeded.

Примечания:

The InitialTime parameter is used to populate the emitter with particles before it's first displayed on screen. Don't use too long time not to delay the game execution.

на счет Random:

это из руководства:

Random (From, To)

Returns a pseudo-random number from a specified range

Параметры:

From

The lower bound of the range

To

The higher bound of the range

а вот пример из демки с Тринити:

on "footstep"
{
this.PlaySound("sounds\footstep" + Random(1, 3) + ".ogg");
}

или вот:

switch ®
{
case 1:
tmp.X=200;
tmp.Y=Random(10,580);
break;
...