Although I haven't spent so much time writing the game today, I'm glad I've got my head around the GMS view system, and I feel I know my way around my game better. I also implemented a semi intelligent enemy - thanks to the 'Gamemaker Language' book by Heartbeast. 

I think at this point I have a viable game, what I need to do is make it more engaging. For this I need to have a variety of enemies with different attack patterns, progressive difficulty, a power-up system, and a weapons and fuel collection system. These should all start to make the game feel a little more like Desert Strike. Longer term I would like to add a mission briefing screen and a minimap/radar too - I'm also tempted to add a strafing capability.

I think tomorrow the first thing I will fix is to allow the view to glide ahead of the player when you slow down, this should stop the enemies surprising you as you move towards them.

If you want to toggle display of the enemy chase and attack range circles tap 'R'

Achievements today

Added enemy with patrol, chase and attack states

Prevented items from spawning on top of each other

Fixed the views so the level is now my longer vertically and sharper

Add screenshake

Added collision with enemy causes death

Replaced the mountain graphic - I actually found a nice spritesheet with about 10 different mountains which I need to integrate into the game