I made an example of that some time ago for someone, I'll see if I can find it..

Basically it does what Beaverlicious says.

It was my tablet-keyboard acting funny..

Sorry..

Create a variable StartY and on start of layout set it to object.y

Create a variable Altitude and every tick set it to round(abs(object.y-StartY))

Edit: Removed "de" (stupid swype keyboard!)

I was actually thinking of using pin-behaviour for it..

You could also do the offset way, it's just preference..

if you create a sprite at touch.x,touch.y with drag and drop behaviour, pin the ship to it and on touch end destroy the sprite.. should work..

Create a variable StartY and on start of layout set it to player.y

Create a variable Score and every tick set it to round(abs(player.y-StartY))

looks like simple drag and drop behaviour with offset.

either create a sprite on touch with drag and drop and pin it to the ship position sprite, or create offsetx and offsety variables and position the ship acording to touch.x-offsetx and touch.y-offsety.

to compare the distance you can use

distance(zombie.x, zombie.y, player.x, player.y)

Use the is pinned condition, right click and choose invert to make the is not pinned condition.

You don't have to buy the paid version if you let others make your games.

It is very possible to create this, so if you put in the effort to show you've tried and make the game untill your understanding of events stops you, people might want to help you overcome these obstacles.

If you have trouble getting started, you might like the ghost shooter tutorial, following that you'll learn a lot about events and the game might even be a bit like what you want to create.

What part of the zombie-movement will you need help with?

What behaviour are you using?

Is the player the zombie or are the enemies?

Is the game top-down or from the side?

Have you implemented the line of sight yet or will you be using pathfinder behaviour?

Please send a capx for us to improve upon.

It probably is your collision polygon.

If your polygon has different shapes on different animation-frames there is a good change that in one of those frames the polygon suddenly overlaps the ground and your player gets stuck.

To test this just go to the first frame of your animation and apply polygon to the whole animation.

It could onfcourse also be a misplaced origin point..