Make more enemies spawn over time?

Hi Everyone, I'm trying to put together a simple "stay alive as long as possible" style game.

I've made a set of enemies spawn outside the layout and move across the screen, the players goal is to avoid the enemies. My problem I have is I have no idea how to make the enemies go from spawning a random amount every second to after 20/30 seconds change this to spawning a random amount every 0.5 seconds.

I'd then like to be able to keep speeding the spawn rates up every 20/30 seconds or so.

Is something like this possible to do? Here's a screenshot of what i've put together, (probably completely wrong).

i.imgur.com/vpVuOL2.png

Any tips to make this happen would be great!

every 20 seconds set TIME_VAR(global variable)

spawn enemy every TIME_VAR

Hi Everyone, I'm trying to put together a simple "stay alive as long as possible" style game.

I've made a set of enemies spawn outside the layout and move across the screen, the players goal is to avoid the enemies. My problem I have is I have no idea how to make the enemies go from spawning a random amount every second to after 20/30 seconds change this to spawning a random amount every 0.5 seconds.

I'd then like to be able to keep speeding the spawn rates up every 20/30 seconds or so.

Is something like this possible to do? Here's a screenshot of what i've put together, (probably completely wrong).

http://i.imgur.com/vpVuOL2.png

Any tips to make this happen would be great!

A good way to do it would be to firstly have two global variables;

interval

respawnRate

So, every "interval" seconds, you decrease "respawnRate", which stores your enemy spawn rate.

<img src="http://s23.postimg.org/4hfk5k0sb/spawn.png" border="0" />

Can you apply something like that to your situation?

exactly what i meant <img src="smileys/smiley2.gif" border="0" align="middle" />

exactly what i meant <img src="smileys/smiley2.gif" border="0" align="middle" />

I completely agree. It was just that by the time I wrote up my reply, you'd already beaten me to it. <img src="smileys/smiley36.gif" border="0" align="middle" />

no problem you got even an example for him <img src="smileys/smiley4.gif" border="0" align="middle" />

Thanks for your replies, you've all been super helpful. I'll give this a go and let you know how I get on.

This worked perfectly, does exactly what I wanted it to. One last thing, is there a way to add a condition onto the end so that when my spawnrate gets to a certain speed it locks at that speed, avoiding it quickening the spawn rate endlessly?

Thanks again for all your help

What you could do is add an event that compares two variables, and then make lowering your respawn rate conditional on its value being more than x;

<img src="http://s10.postimg.org/o0b78mma1/spawn3.png" border="0" />

I'd be interested to know if there's another way to do it, though. Perhaps with the While plugin, although I haven't used that myself yet, so I'm not 100% sure on how it functions.

Edit: Corrected my image. The second condition didn't need to be a sub-event.