I'd be interested to know about this too, since I tried generating wind effects with random spawn times. I gave the Wind object a private variable named "spawn", and set the event up like this:
Every 2000+Wind('spawn') milliseconds ---> Wind: Set 'spawn' to random(5000) System: Create object "Wind" at position X,Y
But it didn't work :( It calculated the random figure for 'spawn' once, and then stuck to that figure for the entire playthrough. Different spawn speed for each playthrough, mind you, so it sort of worked, slightly.
I'm not sure why that doesn't work though. If it did, I imagine your shooting behaviour could work with a similar setup.-Silver-2012-12-12 11:06:07
Just had a thought here. This isn't a perfect solution, but it adds some randomization between different enemies - since your enemies already exist on the layout (I'm assuming you aren't getting the System to create them at run time?) you could set some private variables up for them individually. So for example, give them all a private variable called 'Shoot' and manually set each Enemy's 'Shoot' value to a different number.
For Each Enemy ---> Every 50+Enemy('Shoot')milliseconds ---> System: Create object bullet at Enemy.X, .Y
I haven't tested this, but I think it should work. So an enemy with a 'Shoot' value of 0 would fire every half a second, whilst an enemy with a value of 150 would shoot every 2 seconds.